<para><xref linkend="dbdoclet.50438209_10424"/></para>
</listitem>
<listitem>
- <para><xref xmlns:xlink="http://www.w3.org/1999/xlink" linkend="section_syy_gcl_qk"/></para>
+ <para><xref xmlns:xlink="http://www.w3.org/1999/xlink" linkend="wide_striping"/></para>
</listitem>
</itemizedlist>
<section xml:id="dbdoclet.50438209_79324">
<indexterm>
<primary>space</primary>
<secondary>striping</secondary>
- </indexterm>How Lustre* File System Striping Works</title>
- <para>In a Lustre* file system, the MDS allocates objects to OSTs using either a round-robin
+ </indexterm>How Lustre File System Striping Works</title>
+ <para>In a Lustre file system, the MDS allocates objects to OSTs using either a round-robin
algorithm or a weighted algorithm. When the amount of free space is well balanced (i.e., by
default, when the free space across OSTs differs by less than 17%), the round-robin algorithm
is used to select the next OST to which a stripe is to be written. Periodically, the MDS
objects on OSTs with more free space. (This can reduce I/O performance until space usage is
rebalanced again.) For a more detailed description of how striping is allocated, see <xref
linkend="dbdoclet.50438209_10424"/>.</para>
- <para condition="l22">Files can only be striped over a finite number of OSTs. Prior to the
- Lustre 2.2 release, the maximum number of OSTs that a file could be striped across was limited
- to 160. As of the Lustre 2.2 release, the maximum number of OSTs is 2000. For more
- information, see <xref xmlns:xlink="http://www.w3.org/1999/xlink" linkend="section_syy_gcl_qk"
- />.</para>
+ <para>Files can only be striped over a finite number of OSTs, based on the
+ maximum size of the attributes that can be stored on the MDT. If the MDT
+ is ldiskfs-based without the <literal>ea_inode</literal> feature, a file
+ can be striped across at most 160 OSTs. With a ZFS-based MDT, or if the
+ <literal>ea_inode</literal> feature is enabled for an ldiskfs-based MDT,
+ a file can be striped across up to 2000 OSTs. For more information, see
+ <xref xmlns:xlink="http://www.w3.org/1999/xlink" linkend="wide_striping"/>.
+ </para>
</section>
<section xml:id="dbdoclet.50438209_48033">
<title><indexterm>
<para>The command to create a new file with a specified stripe size is similar to:</para>
<screen>[client]# lfs setstripe -s 4M /mnt/lustre/new_file</screen>
<para>This example command creates the new file <literal>/mnt/lustre/new_file</literal> with a stripe size of 4 MB.</para>
- <para>Now, when a file is created, the new stripe setting evenly distributes the data over all the available OSTs:</para>
+ <para>Now, when the file is created, the new stripe setting creates the file on a single OST with a stripe size of 4M:</para>
<screen> [client]# lfs getstripe /mnt/lustre/new_file
/mnt/lustre/4mb_file
lmm_stripe_count: 1
lmm_stripe_size: 4194304
+lmm_pattern: 1
+lmm_layout_gen: 0
lmm_stripe_offset: 1
obdidx objid objid group
1 690550 0xa8976 0 </screen>
$ lfs getstripe file1
/mnt/testfs/file1
-/mnt/testfs/file1
lmm_stripe_count: 1
lmm_stripe_size: 1048576
+lmm_pattern: 1
+lmm_layout_gen: 0
lmm_stripe_offset: 0
obdidx objid objid group
0 37364 0x91f4 0</screen>
<para>To view information for a file, enter a command similar to:</para>
<screen>$ lfs getstripe /mnt/lustre/foo
/mnt/lustre/foo
+lmm_stripe_count: 1
+lmm_stripe_size: 1048576
+lmm_pattern: 1
+lmm_layout_gen: 0
+lmm_stripe_offset: 0
obdidx objid objid group
2 835487 m0xcbf9f 0 </screen>
<para>In this example, the file is located on <literal>obdidx 2</literal>, which corresponds
<primary>striping</primary>
<secondary>remote directories</secondary>
</indexterm>Locating the MDT for a remote directory</title>
- <para condition="l24">Lustre release 2.4 can be configured with multiple MDTs in the same
- file system. Each sub-directory can have a different MDT. To identify on which MDT a given
- subdirectory is located, pass the <literal>getstripe -M</literal> parameters to
- <literal>lfs</literal>. An example of this command is provided in the section <xref
- linkend="dbdoclet.rmremotedir"/>.</para>
+ <para condition="l24">Lustre software release 2.4 can be configured with
+ multiple MDTs in the same file system. Each sub-directory can have a
+ different MDT. To identify on which MDT a given subdirectory is
+ located, pass the <literal>getstripe [--mdt-index|-M]</literal>
+ parameters to <literal>lfs</literal>. An example of this command is
+ provided in the section <xref linkend="dbdoclet.rmremotedir"/>.</para>
+ </section>
+ </section>
+ <section xml:id="pfl" condition='l2A'>
+ <title><indexterm>
+ <primary>striping</primary>
+ <secondary>PFL</secondary>
+ </indexterm>Progressive File Layout(PFL)</title>
+ <para>The Lustre Progressive File Layout (PFL) feature simplifies the use
+ of Lustre so that users can expect reasonable performance for a variety of
+ normal file IO patterns without the need to explicitly understand their IO
+ model or Lustre usage details in advance. In particular, users do not
+ necessarily need to know the size or concurrency of output files in
+ advance of their creation and explicitly specify an optimal layout for
+ each file in order to achieve good performance for both highly concurrent
+ shared-single-large-file IO or parallel IO to many smaller per-process
+ files. </para>
+ <para>The layout of a PFL file is stored on disk as <literal>composite
+ layout</literal>. A PFL file is essentially an array of
+ <literal>sub-layout components</literal>, with each sub-layout component
+ being a plain layout covering different and non-overlapped extents of
+ the file. For PFL files, the file layout is composed of a series of
+ components, therefore it's possible that there are some file extents are
+ not described by any components.</para>
+ <para>An example of how data blocks of PFL files are mapped to OST objects
+ of components is shown in the following PFL object mapping diagram:</para>
+ <figure xml:id="managinglayout.fig.pfl">
+ <title>PFL object mapping diagram</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" width="100%"
+ fileref="figures/PFL_object_mapping_diagram.png" />
+ </imageobject>
+ <textobject>
+ <phrase>PFL object mapping diagram</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The PFL file in <xref linkend="managinglayout.fig.pfl"/> has 3
+ components and shows the mapping for the blocks of a 2055MB file.
+ The stripe size for the first two components is 1MB, while the stripe size
+ for the third component is 4MB. The stripe count is increasing for each
+ successive component. The first component only has two 1MB blocks and the
+ single object has a size of 2MB. The second component holds the next 254MB
+ of the file spread over 4 separate OST objects in RAID-0, each one will
+ have a size of 256MB / 4 objects = 64MB per object. Note the first two
+ objects <literal>obj 2,0</literal> and <literal>obj 2,1</literal>
+ have a 1MB hole at the start where the data is stored in the first
+ component. The final component holds the next 1800MB spread over 32 OST
+ objects. There is a 256MB / 32 = 8MB hole at the start each one for the
+ data stored in the first two components. Each object will be
+ 2048MB / 32 objects = 64MB per object, except the
+ <literal>obj 3,0</literal> that holds an extra 4MB chunk and
+ <literal>obj 3,1</literal> that holds an extra 3MB chunk. If more data
+ was written to the file, only the objects in component 3 would increase
+ in size.</para>
+ <para>When a file range with defined but not instantiated component is
+ accessed, clients will send a Layout Intent RPC to the MDT, and the MDT
+ would instantiate the objects of the components covering that range.
+ </para>
+ <para>Next, some commands for user to operate PFL files are introduced and
+ some examples of possible composite layout are illustrated as well.
+ Lustre provides commands
+ <literal>lfs setstripe</literal> and <literal>lfs migrate</literal> for
+ users to operate PFL files. <literal>lfs setstripe</literal> commands
+ are used to create PFL files, add or delete components to or from an
+ existing composite file; <literal>lfs migrate</literal> commands are used
+ to re-layout the data in existing files using the new layout parameter by
+ copying the data from the existing OST(s) to the new OST(s). Also,
+ as introduced in the previous sections, <literal>lfs getstripe</literal>
+ commands can be used to list the striping/component information for a
+ given PFL file, and <literal>lfs find</literal> commands can be used to
+ search the directory tree rooted at the given directory or file name for
+ the files that match the given PFL component parameters.</para>
+ <note><para>Using PFL files requires both the client and server to
+ understand the PFL file layout, which isn't available for Lustre 2.9 and
+ earlier. And it will not prevent older clients from accessing non-PFL
+ files in the filesystem.</para></note>
+ <section remap="h3">
+ <title><literal>lfs setstripe</literal></title>
+ <para><literal>lfs setstripe</literal> commands are used to create PFL
+ files, add or delete components to or from an existing composite file.
+ (Suppose we have 8 OSTs in the following examples and stripe size is 1MB
+ by default.)</para>
+ <section remap="h4">
+ <title>Create a PFL file</title>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs setstripe
+[--component-end|-E end1] [STRIPE_OPTIONS]
+[--component-end|-E end2] [STRIPE_OPTIONS] ... <replaceable>filename</replaceable></screen>
+ <para>The <literal>-E</literal> option is used to specify the end offset
+ (in bytes or using a suffix “kMGTP”, e.g. 256M) of each component, and
+ it also indicates the following <literal>STRIPE_OPTIONS</literal> are
+ for this component. Each component defines the stripe pattern of the
+ file in the range of [start, end). The first component must start from
+ offset 0 and all components must be adjacent with each other, no holes
+ are allowed, so each extent will start at the end of previous extent.
+ A <literal>-1</literal> end offset or <literal>eof</literal> indicates
+ this is the last component extending to the end of file.</para>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <screen>$ lfs setstripe -E 4M -c 1 -E 64M -c 4 -E -1 -c -1 -i 4 \
+/mnt/testfs/create_comp</screen>
+ <para>This command creates a file with composite layout illustrated in
+ the following figure. The first component has 1 stripe and covers
+ [0, 4M), the second component has 4 stripes and covers [4M, 64M), and
+ the last component stripes start at OST4, cross over all available
+ OSTs and covers [64M, EOF).</para>
+ <figure xml:id="managinglayout.fig.pfl_create">
+ <title>Example: create a composite file</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_createfile.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: create a composite file</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The composite layout can be output by the following command:</para>
+ <screen>$ lfs getstripe /mnt/testfs/create_comp
+/mnt/testfs/create_comp
+ lcm_layout_gen: 3
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 4194304
+ lmm_stripe_count: 1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 0
+ lmm_objects:
+ - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: 0
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: -1
+ lcme_id: 3
+ lcme_flags: 0
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: -1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 4</screen>
+ <note><para>Only the first component’s OST objects of the PFL file are
+ instantiated when the layout is being set. Other instantiation is
+ delayed to later write/truncate operations.</para></note>
+ <para>If we write 128M data to this PFL file, the second and third
+ components will be instantiated:</para>
+ <screen>$ dd if=/dev/zero of=/mnt/testfs/create_comp bs=1M count=128
+$ lfs getstripe /mnt/testfs/create_comp
+/mnt/testfs/create_comp
+ lcm_layout_gen: 5
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 4194304
+ lmm_stripe_count: 1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 0
+ lmm_objects:
+ - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 1
+ lmm_objects:
+ - 0: { l_ost_idx: 1, l_fid: [0x100010000:0x2:0x0] }
+ - 1: { l_ost_idx: 2, l_fid: [0x100020000:0x2:0x0] }
+ - 2: { l_ost_idx: 3, l_fid: [0x100030000:0x2:0x0] }
+ - 3: { l_ost_idx: 4, l_fid: [0x100040000:0x2:0x0] }
+
+ lcme_id: 3
+ lcme_flags: init
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: 8
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 4
+ lmm_objects:
+ - 0: { l_ost_idx: 4, l_fid: [0x100040000:0x3:0x0] }
+ - 1: { l_ost_idx: 5, l_fid: [0x100050000:0x2:0x0] }
+ - 2: { l_ost_idx: 6, l_fid: [0x100060000:0x2:0x0] }
+ - 3: { l_ost_idx: 7, l_fid: [0x100070000:0x2:0x0] }
+ - 4: { l_ost_idx: 0, l_fid: [0x100000000:0x3:0x0] }
+ - 5: { l_ost_idx: 1, l_fid: [0x100010000:0x3:0x0] }
+ - 6: { l_ost_idx: 2, l_fid: [0x100020000:0x3:0x0] }
+ - 7: { l_ost_idx: 3, l_fid: [0x100030000:0x3:0x0] }</screen>
+ </section>
+ <section remap="h4">
+ <title>Add component(s) to an existing composite file</title>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs setstripe --component-add
+[--component-end|-E end1] [STRIPE_OPTIONS]
+[--component-end|-E end2] [STRIPE_OPTIONS] ... <replaceable>filename</replaceable></screen>
+ <para>The option <literal>--component-add</literal> is used to add
+ components to an existing composite file. The extent start of
+ the first component to be added is equal to the extent end of last
+ component in the existing file, and all components to be added must
+ be adjacent with each other.</para>
+ <note><para>If the last existing component is specified by
+ <literal>-E -1</literal> or <literal>-E eof</literal>, which covers
+ to the end of the file, it must be deleted before a new one is added.
+ </para></note>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <screen>$ lfs setstripe -E 4M -c 1 -E 64M -c 4 /mnt/testfs/add_comp
+$ lfs setstripe --component-add -E -1 -c 4 -o 6-7,0,5 \
+/mnt/testfs/add_comp</screen>
+ <para>This command adds a new component which starts from the end of
+ the last existing component to the end of file. The layout of this
+ example is illustrated in
+ <xref linkend="managinglayout.fig.pfl_addcomp"/>. The last component
+ stripes across 4 OSTs in sequence OST6, OST7, OST0 and OST5, covers
+ [64M, EOF).</para>
+ <figure xml:id="managinglayout.fig.pfl_addcomp">
+ <title>Example: add a component to an existing composite file</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_addcomp.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: add a component to an existing composite file
+ </phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The layout can be printed out by the following command:</para>
+ <screen>$ lfs getstripe /mnt/testfs/add_comp
+/mnt/testfs/add_comp
+ lcm_layout_gen: 5
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 4194304
+ lmm_stripe_count: 1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 0
+ lmm_objects:
+ - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 1
+ lmm_objects:
+ - 0: { l_ost_idx: 1, l_fid: [0x100010000:0x2:0x0] }
+ - 1: { l_ost_idx: 2, l_fid: [0x100020000:0x2:0x0] }
+ - 2: { l_ost_idx: 3, l_fid: [0x100030000:0x2:0x0] }
+ - 3: { l_ost_idx: 4, l_fid: [0x100040000:0x2:0x0] }
+
+ lcme_id: 5
+ lcme_flags: 0
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: -1</screen>
+ <para>The component ID "lcme_id" changes as layout generation
+ changes. It is not necessarily sequential and does not imply ordering
+ of individual components.</para>
+ <note><para>Similar to specifying a full-file composite layout at file
+ creation time, <literal>--component-add</literal> won't instantiate
+ OST objects, the instantiation is delayed to later write/truncate
+ operations. For example, after writing beyond the 64MB start of the
+ file's last component, the new component has had objects allocated:
+ </para></note>
+ <screen>$ lfs getstripe -I5 /mnt/testfs/add_comp
+/mnt/testfs/add_comp
+ lcm_layout_gen: 6
+ lcm_entry_count: 3
+ lcme_id: 5
+ lcme_flags: init
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 6
+ lmm_objects:
+ - 0: { l_ost_idx: 6, l_fid: [0x100060000:0x4:0x0] }
+ - 1: { l_ost_idx: 7, l_fid: [0x100070000:0x4:0x0] }
+ - 2: { l_ost_idx: 0, l_fid: [0x100000000:0x5:0x0] }
+ - 3: { l_ost_idx: 5, l_fid: [0x100050000:0x4:0x0] }</screen>
+ </section>
+ <section remap="h4">
+ <title>Delete component(s) from an existing file</title>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs setstripe --component-del
+[--component-id|-I comp_id | --component-flags comp_flags]
+<replaceable>filename</replaceable></screen>
+ <para>The option <literal>--component-del</literal> is used to remove
+ the component(s) specified by component ID or flags from an existing
+ file. This operation will result in any data stored in the deleted
+ component will be lost.</para>
+ <para>The ID specified by <literal>-I</literal> option is the numerical
+ unique ID of the component, which can be obtained by command
+ <literal>lfs getstripe -I</literal> command, and the flag specified by
+ <literal>--component-flags</literal> option is a certain type of
+ components, which can be obtained by command
+ <literal>lfs getstripe --component-flags</literal>. For now, we only
+ have two flags <literal>init</literal> and <literal>^init</literal>
+ for instantiated and un-instantiated components respectively.</para>
+ <note><para>Deletion must start with the last component because hole is
+ not allowed.</para></note>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <screen>$ lfs getstripe -I /mnt/testfs/del_comp
+1
+2
+5
+$ lfs setstripe --component-del -I 5 /mnt/testfs/del_comp</screen>
+ <para>This example deletes the component with ID 5 from file
+ <literal>/mnt/testfs/del_comp</literal>. If we still use the last
+ example, the final result is illustrated in
+ <xref linkend="managinglayout.fig.pfl_delcomp"/>.</para>
+ <figure xml:id="managinglayout.fig.pfl_delcomp">
+ <title>Example: delete a component from an existing file</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_delcomp.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: delete a component from an existing file</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>If you try to delete a non-last component, you will see the
+ following error:</para>
+ <screen>$ lfs setstripe -component-del -I 2 /mnt/testfs/del_comp
+Delete component 0x2 from /mnt/testfs/del_comp failed. Invalid argument
+error: setstripe: delete component of file '/mnt/testfs/del_comp' failed: Invalid argument</screen>
+ </section>
+ <section remap="h4">
+ <title>Set default PFL layout to an existing directory</title>
+ <para>Similar to create a PFL file, you can set default PFL layout to
+ an existing directory. After that, all the files created will inherit
+ this layout by default.</para>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs setstripe
+[--component-end|-E end1] [STRIPE_OPTIONS]
+[--component-end|-E end2] [STRIPE_OPTIONS] ... <replaceable>dirname</replaceable></screen>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <screen>
+$ mkdir /mnt/testfs/pfldir
+$ lfs setstripe -E 256M -c 1 -E 16G -c 4 -E -1 -S 4M -c -1 /mnt/testfs/pfldir
+</screen>
+ <para>When you run <literal>lfs getstripe</literal>, you will see:
+ </para>
+ <screen>
+$ lfs getstripe /mnt/testfs/pfldir
+/mnt/testfs/pfldir
+ lcm_layout_gen: 0
+ lcm_entry_count: 3
+ lcme_id: N/A
+ lcme_flags: 0
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 268435456
+ stripe_count: 1 stripe_size: 1048576 stripe_offset: -1
+ lcme_id: N/A
+ lcme_flags: 0
+ lcme_extent.e_start: 268435456
+ lcme_extent.e_end: 17179869184
+ stripe_count: 4 stripe_size: 1048576 stripe_offset: -1
+ lcme_id: N/A
+ lcme_flags: 0
+ lcme_extent.e_start: 17179869184
+ lcme_extent.e_end: EOF
+ stripe_count: -1 stripe_size: 4194304 stripe_offset: -1
+</screen>
+ <para>If you create a file under <literal>/mnt/testfs/pfldir</literal>,
+ the layout of that file will inherit the layout from its parent
+ directory:</para>
+ <screen>
+$ touch /mnt/testfs/pfldir/pflfile
+$ lfs getstripe /mnt/testfs/pfldir/pflfile
+/mnt/testfs/pfldir/pflfile
+ lcm_layout_gen: 2
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 268435456
+ lmm_stripe_count: 1
+ lmm_stripe_size: 1048576
+ lmm_pattern: raid0
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 1
+ lmm_objects:
+ - 0: { l_ost_idx: 1, l_fid: [0x100010000:0xa:0x0] }
+
+ lcme_id: 2
+ lcme_flags: 0
+ lcme_extent.e_start: 268435456
+ lcme_extent.e_end: 17179869184
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: raid0
+ lmm_layout_gen: 0
+ lmm_stripe_offset: -1
+
+ lcme_id: 3
+ lcme_flags: 0
+ lcme_extent.e_start: 17179869184
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: -1
+ lmm_stripe_size: 4194304
+ lmm_pattern: raid0
+ lmm_layout_gen: 0
+ lmm_stripe_offset: -1
+</screen>
+ <note><para>
+ <literal>lfs setstripe --component-add/del</literal> can't be run
+ on a directory, because default layout in directory is likea config,
+ which can be arbitrarily changed by <literal>lfs setstripe</literal>,
+ while layout in file may have data (OST objects) attached. If you want
+ to delete default layout in a directory, run
+ <literal>lfs setstripe -d <replaceable>dirname</replaceable></literal>
+ to return the directory to the filesystem-wide defaults, like:
+ <screen>
+$ lfs setstripe -d /mnt/testfs/pfldir
+$ lfs getstripe -d /mnt/testfs/pfldir
+/mnt/testfs/pfldir
+stripe_count: 1 stripe_size: 1048576 stripe_offset: -1
+/mnt/testfs/pfldir/commonfile
+lmm_stripe_count: 1
+lmm_stripe_size: 1048576
+lmm_pattern: 1
+lmm_layout_gen: 0
+lmm_stripe_offset: 0
+ obdidx objid objid group
+ 2 9 0x9 0
+</screen>
+ </para></note>
+ </section>
+ </section>
+ <section remap="h3">
+ <title><literal>lfs migrate</literal></title>
+ <para><literal>lfs migrate</literal> commands are used to re-layout the
+ data in the existing files with the new layout parameter by copying the
+ data from the existing OST(s) to the new OST(s).</para>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs migrate [--component-end|-E comp_end] [STRIPE_OPTIONS] ...
+<replaceable>filename</replaceable></screen>
+ <para>The difference between <literal>migrate</literal> and
+ <literal>setstripe</literal> is that <literal>migrate</literal> is to
+ re-layout the data in the existing files, while
+ <literal>setstripe</literal> is to create new files with the specified
+ layout.</para>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <para><emphasis role="bold">Case1. Migrate a normal one to a composite
+ layout</emphasis></para>
+ <screen>$ lfs setstripe -c 1 -S 128K /mnt/testfs/norm_to_2comp
+$ dd if=/dev/urandom of=/mnt/testfs/norm_to_2comp bs=1M count=5
+$ lfs getstripe /mnt/testfs/norm_to_2comp --yaml
+/mnt/testfs/norm_to_comp
+lmm_stripe_count: 1
+lmm_stripe_size: 131072
+lmm_pattern: 1
+lmm_layout_gen: 0
+lmm_stripe_offset: 7
+lmm_objects:
+ - l_ost_idx: 7
+ l_fid: 0x100070000:0x2:0x0
+$ lfs migrate -E 1M -S 512K -c 1 -E -1 -S 1M -c 2 \
+/mnt/testfs/norm_to_2comp</screen>
+ <para>In this example, a 5MB size file with 1 stripe and 128K stripe size
+ is migrated to a composite layout file with 2 components, illustrated in
+ <xref linkend="managinglayout.fig.pfl_norm_to_comp"/>.</para>
+ <figure xml:id="managinglayout.fig.pfl_norm_to_comp">
+ <title>Example: migrate normal to composite</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_norm_to_comp.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: migrate normal to composite</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The stripe information after migration is like:</para>
+ <screen>$ lfs getstripe /mnt/testfs/norm_to_2comp
+/mnt/testfs/norm_to_2comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 2
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 1048576
+ lmm_stripe_count: 1
+ lmm_stripe_size: 524288
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 0
+ lmm_objects:
+ - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 1048576
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: 2
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 2
+ lmm_objects:
+ - 0: { l_ost_idx: 2, l_fid: [0x100020000:0x2:0x0] }
+ - 1: { l_ost_idx: 3, l_fid: [0x100030000:0x2:0x0] }</screen>
+ <para><emphasis role="bold">Case2. Migrate a composite layout to another
+ composite layout</emphasis></para>
+ <screen>$ lfs setstripe -E 1M -S 512K -c 1 -E -1 -S 1M -c 2 \
+/mnt/testfs/2comp_to_3comp
+$ dd if=/dev/urandom of=/mnt/testfs/norm_to_2comp bs=1M count=5
+$ lfs migrate -E 1M -S 1M -c 2 -E 4M -S 1M -c 2 -E -1 -S 3M -c 3 \
+/mnt/testfs/2comp_to_3comp</screen>
+ <para>In this example, a composite layout file with 2 components is
+ migrated a composite layout file with 3 components. If we still use
+ the example in case1, the migration process is illustrated in
+ <xref linkend="managinglayout.fig.pfl_comp_to_comp"/>.</para>
+ <figure xml:id="managinglayout.fig.pfl_comp_to_comp">
+ <title>Example: migrate composite to composite</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_comp_to_comp.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: migrate composite to composite</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The stripe information is like:</para>
+ <screen>$ lfs getstripe /mnt/testfs/2comp_to_3comp
+/mnt/testfs/2comp_to_3comp
+ lcm_layout_gen: 6
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 1048576
+ lmm_stripe_count: 2
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 4
+ lmm_objects:
+ - 0: { l_ost_idx: 4, l_fid: [0x100040000:0x2:0x0] }
+ - 1: { l_ost_idx: 5, l_fid: [0x100050000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 1048576
+ lcme_extent.e_end: 4194304
+ lmm_stripe_count: 2
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 6
+ lmm_objects:
+ - 0: { l_ost_idx: 6, l_fid: [0x100060000:0x2:0x0] }
+ - 1: { l_ost_idx: 7, l_fid: [0x100070000:0x3:0x0] }
+
+ lcme_id: 3
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: 3
+ lmm_stripe_size: 3145728
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 0
+ lmm_objects:
+ - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x3:0x0] }
+ - 1: { l_ost_idx: 1, l_fid: [0x100010000:0x2:0x0] }
+ - 2: { l_ost_idx: 2, l_fid: [0x100020000:0x3:0x0] }</screen>
+ <para><emphasis role="bold">Case3. Migrate a composite layout to a
+ normal one</emphasis></para>
+ <screen>$ lfs migrate -E 1M -S 1M -c 2 -E 4M -S 1M -c 2 -E -1 -S 3M -c 3 \
+/mnt/testfs/3comp_to_norm
+$ dd if=/dev/urandom of=/mnt/testfs/norm_to_2comp bs=1M count=5
+$ lfs migrate -c 2 -S 2M /mnt/testfs/3comp_to_normal</screen>
+ <para>In this example, a composite file with 3 components is migrated to
+ a normal file with 2 stripes and 2M stripe size. If we still use the
+ example in Case2, the migration process is illustrated in
+ <xref linkend="managinglayout.fig.pfl_comp_to_norm"/>.</para>
+ <figure xml:id="managinglayout.fig.pfl_comp_to_norm">
+ <title>Example: migrate composite to normal</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata scalefit="1" depth="2.75in" align="center"
+ fileref="figures/PFL_comp_to_norm.png" />
+ </imageobject>
+ <textobject>
+ <phrase>Example: migrate composite to normal</phrase>
+ </textobject>
+ </mediaobject>
+ </figure>
+ <para>The stripe information is like:</para>
+ <screen>$ lfs getstripe /mnt/testfs/3comp_to_norm --yaml
+/mnt/testfs/3comp_to_norm
+lmm_stripe_count: 2
+lmm_stripe_size: 2097152
+lmm_pattern: 1
+lmm_layout_gen: 7
+lmm_stripe_offset: 4
+lmm_objects:
+ - l_ost_idx: 4
+ l_fid: 0x100040000:0x3:0x0
+ - l_ost_idx: 5
+ l_fid: 0x100050000:0x3:0x0</screen>
+ </section>
+ <section remap="h3">
+ <title><literal>lfs getstripe</literal></title>
+ <para><literal>lfs getstripe</literal> commands can be used to list the
+ striping/component information for a given PFL file. Here, only those
+ parameters new for PFL files are shown.</para>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs getstripe
+[--component-id|-I [comp_id]]
+[--component-flags [comp_flags]]
+[--component-count]
+[--component-start [+-][N][kMGTPE]]
+[--component-end|-E [+-][N][kMGTPE]]
+<replaceable>dirname|filename</replaceable></screen>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <para>Suppose we already have a composite file
+ <literal>/mnt/testfs/3comp</literal>, created by the following
+ command:</para>
+ <screen>$ lfs setstripe -E 4M -c 1 -E 64M -c 4 -E -1 -c -1 -i 4 \
+/mnt/testfs/3comp</screen>
+ <para>And write some data</para>
+ <screen>$ dd if=/dev/zero of=/mnt/testfs/3comp bs=1M count=5</screen>
+ <para><emphasis role="bold">Case1. List component ID and its related
+ information</emphasis></para>
+ <itemizedlist>
+ <listitem>
+ <para>List all the components ID</para>
+ <screen>$ lfs getstripe -I /mnt/testfs/3comp
+1
+2
+3</screen>
+ </listitem>
+ <listitem>
+ <para>List the detailed striping information of component ID=2</para>
+ <screen>$ lfs getstripe -I2 /mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 5
+ lmm_objects:
+ - 0: { l_ost_idx: 5, l_fid: [0x100050000:0x2:0x0] }
+ - 1: { l_ost_idx: 6, l_fid: [0x100060000:0x2:0x0] }
+ - 2: { l_ost_idx: 7, l_fid: [0x100070000:0x2:0x0] }
+ - 3: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }</screen>
+ </listitem>
+ <listitem>
+ <para>List the stripe offset and stripe count of component ID=2</para>
+ <screen>$ lfs getstripe -I2 -i -c /mnt/testfs/3comp
+ lmm_stripe_count: 4
+ lmm_stripe_offset: 5</screen>
+ </listitem>
+ </itemizedlist>
+ <para><emphasis role="bold">Case2. List the component which contains the
+ specified flag</emphasis></para>
+ <itemizedlist>
+ <listitem>
+ <para>List the flag of each component</para>
+ <screen>$ lfs getstripe -component-flag -I /mnt/testfs/3comp
+ lcme_id: 1
+ lcme_flags: init
+ lcme_id: 2
+ lcme_flags: init
+ lcme_id: 3
+ lcme_flags: 0</screen>
+ </listitem>
+ <listitem>
+ <para>List component(s) who is not instantiated</para>
+ <screen>$ lfs getstripe --component-flags=^init /mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 3
+ lcme_flags: 0
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: -1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 4
+ lmm_stripe_offset: 4</screen>
+ </listitem>
+ </itemizedlist>
+ <para><emphasis role="bold">Case3. List the total number of all the
+ component(s)</emphasis></para>
+ <itemizedlist>
+ <listitem>
+ <para>List the total number of all the components</para>
+ <screen>$ lfs getstripe --component-count /mnt/testfs/3comp
+3</screen>
+ </listitem>
+ </itemizedlist>
+ <para><emphasis role="bold">Case4. List the component with the specified
+ extent start or end positions</emphasis></para>
+ <itemizedlist>
+ <listitem>
+ <para>List the start position in bytes of each component</para>
+ <screen>$ lfs getstripe --component-start /mnt/testfs/3comp
+0
+4194304
+67108864</screen>
+ </listitem>
+ <listitem>
+ <para>List the start position in bytes of component ID=3</para>
+ <screen>$ lfs getstripe --component-start -I3 /mnt/testfs/3comp
+67108864</screen>
+ </listitem>
+ <listitem>
+ <para>List the component with start = 64M</para>
+ <screen>$ lfs getstripe --component-start=64M /mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 3
+ lcme_flags: 0
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: -1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 4
+ lmm_stripe_offset: 4</screen>
+ </listitem>
+ <listitem>
+ <para>List the component(s) with start > 5M</para>
+ <screen>$ lfs getstripe --component-start=+5M /mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 3
+ lcme_flags: 0
+ lcme_extent.e_start: 67108864
+ lcme_extent.e_end: EOF
+ lmm_stripe_count: -1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 4
+ lmm_stripe_offset: 4</screen>
+ </listitem>
+ <listitem>
+ <para>List the component(s) with start < 5M</para>
+ <screen>$ lfs getstripe --component-start=-5M /mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 1
+ lcme_flags: init
+ lcme_extent.e_start: 0
+ lcme_extent.e_end: 4194304
+ lmm_stripe_count: 1
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 4
+ lmm_objects:
+ - 0: { l_ost_idx: 4, l_fid: [0x100040000:0x2:0x0] }
+
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 5
+ lmm_objects:
+ - 0: { l_ost_idx: 5, l_fid: [0x100050000:0x2:0x0] }
+ - 1: { l_ost_idx: 6, l_fid: [0x100060000:0x2:0x0] }
+ - 2: { l_ost_idx: 7, l_fid: [0x100070000:0x2:0x0] }
+ - 3: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }</screen>
+ </listitem>
+ <listitem>
+ <para>List the component(s) with start > 3M and end < 70M</para>
+ <screen>$ lfs getstripe --component-start=+3M --component-end=-70M \
+/mnt/testfs/3comp
+/mnt/testfs/3comp
+ lcm_layout_gen: 4
+ lcm_entry_count: 3
+ lcme_id: 2
+ lcme_flags: init
+ lcme_extent.e_start: 4194304
+ lcme_extent.e_end: 67108864
+ lmm_stripe_count: 4
+ lmm_stripe_size: 1048576
+ lmm_pattern: 1
+ lmm_layout_gen: 0
+ lmm_stripe_offset: 5
+ lmm_objects:
+ - 0: { l_ost_idx: 5, l_fid: [0x100050000:0x2:0x0] }
+ - 1: { l_ost_idx: 6, l_fid: [0x100060000:0x2:0x0] }
+ - 2: { l_ost_idx: 7, l_fid: [0x100070000:0x2:0x0] }
+ - 3: { l_ost_idx: 0, l_fid: [0x100000000:0x2:0x0] }</screen>
+ </listitem>
+ </itemizedlist>
+ </section>
+ <section remap="h3">
+ <title><literal>lfs find</literal></title>
+ <para><literal>lfs find</literal> commands can be used to search the
+ directory tree rooted at the given directory or file name for the files
+ that match the given PFL component parameters. Here, only those
+ parameters new for PFL files are shown. Their usages are similar to
+ <literal>lfs getstripe</literal> commands.</para>
+ <para><emphasis role="bold">Command</emphasis></para>
+ <screen>lfs find <replaceable>directory|filename</replaceable>
+[[!] --component-count [+-=]<replaceable>comp_cnt</replaceable>]
+[[!] --component-start [+-=]<replaceable>N</replaceable>[kMGTPE]]
+[[!] --component-end|-E [+-=]<replaceable>N</replaceable>[kMGTPE]]
+[[!] --component-flags=<replaceable>comp_flags</replaceable>]</screen>
+ <note><para>If you use <literal>--component-xxx</literal> options, only
+ the composite files will be searched; but if you use
+ <literal>! --component-xxx</literal> options, all the files will be
+ searched.</para></note>
+ <para><emphasis role="bold">Example</emphasis></para>
+ <para>We use the following directory and composite files to show how
+ <literal>lfs find</literal> works.</para>
+ <screen>$ mkdir /mnt/testfs/testdir
+$ lfs setstripe -E 1M -E 10M -E eof /mnt/testfs/testdir/3comp
+$ lfs setstripe -E 4M -E 20M -E 30M -E eof /mnt/testfs/testdir/4comp
+$ mkdir -p /mnt/testfs/testdir/dir_3comp
+$ lfs setstripe -E 6M -E 30M -E eof /mnt/testfs/testdir/dir_3comp
+$ lfs setstripe -E 8M -E eof /mnt/testfs/testdir/dir_3comp/2comp
+$ lfs setstripe -c 1 /mnt/testfs/testdir/dir_3comp/commnfile</screen>
+ <para><emphasis role="bold">Case1. Find the files that match the specified
+ component count condition</emphasis></para>
+ <para>Find the files under directory /mnt/testfs/testdir whose number of
+ components is not equal to 3.</para>
+ <screen>$ lfs find /mnt/testfs/testdir ! --component-count=3
+/mnt/testfs/testdir
+/mnt/testfs/testdir/4comp
+/mnt/testfs/testdir/dir_3comp/2comp
+/mnt/testfs/testdir/dir_3comp/commonfile</screen>
+ <para><emphasis role="bold">Case2. Find the files/dirs that match the
+ specified component start/end condition</emphasis></para>
+ <para>Find the file(s) under directory /mnt/testfs/testdir with component
+ start = 4M and end < 70M</para>
+ <screen>$ lfs find /mnt/testfs/testdir --component-start=4M -E -30M
+/mnt/testfs/testdir/4comp</screen>
+ <para><emphasis role="bold">Case3. Find the files/dirs that match the
+ specified component flag condition</emphasis></para>
+ <para>Find the file(s) under directory /mnt/testfs/testdir whose component
+ flags contain <literal>init</literal></para>
+ <screen>$ lfs find /mnt/testfs/testdir --component-flag=init
+/mnt/testfs/testdir/3comp
+/mnt/testfs/testdir/4comp
+/mnt/testfs/testdir/dir_3comp/2comp</screen>
+ <note><para>Since <literal>lfs find</literal> uses
+ "<literal>!</literal>" to do negative search, we don’t support
+ flag <literal>^init</literal> here.</para></note>
</section>
</section>
<section xml:id="dbdoclet.50438209_10424">
preference to location (spreading out stripes across OSSs to increase network bandwidth
utilization) and the weighted allocator gives preference to available space (balancing loads
across OSTs). Threshold and weighting factors for these two algorithms can be adjusted by the
- user. This section describes how to check available free space on disks and how free space is
+ user. The MDT reserves 0.1 percent of total OST space and 32 inodes for each OST. The MDT
+ stops object allocation for the OST if available space is less than reserved or the OST has
+ fewer than 32 free inodes. The MDT starts object allocation when available space is twice
+ as big as the reserved space and the OST has more than 64 free inodes. Note, clients
+ could append existing files no matter what object allocation state is.</para>
+ <para condition="l29"> The reserved space for each OST can be adjusted by the user. Use the
+ <literal>lctl set_param</literal> command, for example the next command reserve 1GB space
+ for all OSTs.
+ <screen>lctl set_param -P osp.*.reserved_mb_low=1024</screen></para>
+ <para>This section describes how to check available free space on disks and how free space is
allocated. It then describes how to set the threshold and weighting factors for the allocation
algorithms.</para>
- <section xml:id="dbdoclet.50438209_35838">
+ <section xml:id="dbdoclet.checking_free_space">
<title>Checking File System Free Space</title>
<para>Free space is an important consideration in assigning file stripes. The <literal>lfs
df</literal> command can be used to show available disk space on the mounted Lustre file
<note>
<para>The <literal>df -i</literal> and <literal>lfs df -i</literal> commands show the
<emphasis role="italic">minimum</emphasis> number of inodes that can be created in the
- file system at the current time. Depending on the current state of the file system and the
- OSTs, it may be possible to create more inodes than currently reported by <literal>df
- -i</literal>. As more files are created in the file system, <literal>df -i</literal>
- will show the current estimated free inode count.</para>
- <para>If the underlying file system has fewer free blocks than inodes, the total inode count
- reported for the file system is only as many inodes as there are free blocks. This is
- because the Lustre file system may need to store an external attribute for each new inode,
- and it is better to report a free inode count that corresponds to the guaranteed minimum
- number of inodes that can be created.</para>
- <para>If the total number of objects available across all of the OSTs is smaller than those
- available on the MDT(s), taking into account the default file striping, then <literal>df
- -i</literal> will also report a smaller number of inodes than could be created. Running
- <literal>lfs df -i</literal> will report the actual number of inodes that are free on
- each target.</para>
+ file system at the current time. If the total number of objects available across all of
+ the OSTs is smaller than those available on the MDT(s), taking into account the default
+ file striping, then <literal>df -i</literal> will also report a smaller number of inodes
+ than could be created. Running <literal>lfs df -i</literal> will report the actual number
+ of inodes that are free on each target.</para>
<para>For ZFS file systems, the number of inodes that can be created is dynamic and depends
on the free space in the file system. The Free and Total inode counts reported for a ZFS
file system are only an estimate based on the current usage for each target. The Used
<literal>/proc/fs/<replaceable>fsname</replaceable>/lov/<replaceable>fsname</replaceable>-mdtlov/qos_threshold_rr</literal>. </para>
<para>To set the <literal>qos_threshold_r</literal> to <literal>25</literal>, enter this
command on the
- MGS:<screen>lctl set_param lov.<replaceable>fsname</replaceable>-mdtlov.quos_threshold_rr=25</screen></para>
+ MGS:<screen>lctl set_param lov.<replaceable>fsname</replaceable>-mdtlov.qos_threshold_rr=25</screen></para>
</section>
<section remap="h3">
<title><indexterm>
of free space available on each OST and less on how stripes are distributed across OSTs. The
default value is <literal>91</literal> (percent). When the free space priority is set to
<literal>100</literal> (percent), weighting is based entirely on free space and location
- is no longer used by the striping algorthm. </para>
+ is no longer used by the striping algorithm. </para>
<para>To change the allocator weighting to <literal>100</literal>, enter this command on the
MGS:</para>
<screen>lctl conf_param <replaceable>fsname</replaceable>-MDT0000.lov.qos_prio_free=100</screen>
</note>
</section>
</section>
- <section xml:id="section_syy_gcl_qk">
+ <section xml:id="wide_striping">
<title><indexterm>
<primary>striping</primary>
<secondary>wide striping</secondary>
</indexterm><indexterm>
<primary>wide striping</primary>
</indexterm>Lustre Striping Internals</title>
- <para>For Lustre releases prior to Lustre release 2.2, files can be striped across a maximum of
- 160 OSTs. Lustre inodes use an extended attribute to record the location of each object (the
- object ID and the number of the OST on which it is stored). The size of the extended attribute
- limits the maximum stripe count to 160 objects.</para>
- <para condition="l22">In Lustre release 2.2 and subsequent releases, the maximum number of OSTs
- over which files can be striped has been raised to 2000 by allocating a new block on which to
- store the extended attribute that holds the object information. This feature, known as "wide
- striping," only allocates the additional extended attribute data block if the file is striped
- with a stripe count greater than 160. The file layout (object ID, OST number) is stored on the
- new data block with a pointer to this block stored in the original Lustre inode for the file.
- For files smaller than 160 objects, the Lustre inode is used to store the file layout.</para>
+ <para>Individual files can only be striped over a finite number of OSTs,
+ based on the maximum size of the attributes that can be stored on the MDT.
+ If the MDT is ldiskfs-based without the <literal>ea_inode</literal>
+ feature, a file can be striped across at most 160 OSTs. With ZFS-based
+ MDTs, or if the <literal>ea_inode</literal> feature is enabled for an
+ ldiskfs-based MDT, a file can be striped across up to 2000 OSTs.
+ </para>
+ <para>Lustre inodes use an extended attribute to record on which OST each
+ object is located, and the identifier each object on that OST. The size of
+ the extended attribute is a function of the number of stripes.</para>
+ <para>If using an ldiskfs-based MDT, the maximum number of OSTs over which
+ files can be striped can been raised to 2000 by enabling the
+ <literal>ea_inode</literal> feature on the MDT:
+ <screen>tune2fs -O ea_inode /dev/<replaceable>mdtdev</replaceable></screen>
+ </para>
+ <note><para>The maximum stripe count for a single file does not limit the
+ maximum number of OSTs that are in the filesystem as a whole, only the
+ maximum possible size and maximum aggregate bandwidth for the file.
+ </para></note>
</section>
</chapter>
git://git.whamcloud.com / doc / manual.git / blobdiff