new subdirectories at the time they are created.</para>
</glossdef>
</glossentry>
- <glossentry xml:id="DNE">
+ <glossentry xml:id="DNE" condition='l24'>
<glossterm>Distributed namespace (DNE)</glossterm>
<glossdef>
- <para>A collection of metadata targets implementing a single file
- system namespace.</para>
+ <para>A collection of metadata targets serving a single file
+ system namespace. Prior to DNE, Lustre file systems were limited to a
+ single metadata target for the entire name space. Without the ability
+ to distribute metadata load over multiple targets, Lustre file system
+ performance is limited. Lustre was enhanced with DNE functionality in
+ two development phases. After completing the first phase of development
+ in Lustre software version 2.4, <emphasis>Remote Directories</emphasis>
+ allows the metadata for sub-directories to be serviced by an
+ independent MDT(s). After completing the second phase of development in
+ Lustre software version 2.8, <emphasis>Striped Directories</emphasis>
+ allows files in a single directory to be serviced by multiple MDTs.
+ </para>
</glossdef>
</glossentry>
</glossdiv>
<glossentry xml:id="lnd">
<glossterm>LND</glossterm>
<glossdef>
- <para>Lustre network driver. A code module that enables LNET support
+ <para>Lustre network driver. A code module that enables LNet support
over particular transports, such as TCP and various kinds of InfiniBand
networks.</para>
</glossdef>
</glossentry>
<glossentry xml:id="lnet">
- <glossterm>LNET</glossterm>
+ <glossterm>LNet</glossterm>
<glossdef>
<para>Lustre networking. A message passing network protocol capable of
- running and routing through various physical layers. LNET forms the
+ running and routing through various physical layers. LNet forms the
underpinning of LNETrpc.</para>
</glossdef>
</glossentry>
<glossterm>MDC</glossterm>
<glossdef>
<para>Metadata client. A Lustre client component that sends metadata
- requests via RPC over LNET to the metadata target (MDT).</para>
+ requests via RPC over LNet to the metadata target (MDT).</para>
</glossdef>
</glossentry>
<glossentry xml:id="mdd">
<glossentry xml:id="nioapi">
<glossterm>NIO API</glossterm>
<glossdef>
- <para>A subset of the LNET RPC module that implements a library for
+ <para>A subset of the LNet RPC module that implements a library for
sending large network requests, moving buffers with RDMA.</para>
</glossdef>
</glossentry>
<glossentry xml:id="portal">
<glossterm>Portal</glossterm>
<glossdef>
- <para>A service address on an LNET NID that binds requests to a
+ <para>A service address on an LNet NID that binds requests to a
specific request service, such as an MDS, MGS, OSS, or LDLM. Services
may listen on multiple portals to ensure that high priority messages
are not queued behind many slow requests on another portal.</para>
<glossentry xml:id="ptlrpc">
<glossterm>PTLRPC</glossterm>
<glossdef>
- <para>An RPC protocol layered on LNET. This protocol deals with
+ <para>An RPC protocol layered on LNet. This protocol deals with
stateful servers and has exactly-once semantics and built in support
for recovery.</para>
</glossdef>
server restarts.</para>
</glossdef>
</glossentry>
+ <glossentry xml:id="remotedirectories" condition='l24'>
+ <glossterm>Remote directory</glossterm>
+ <glossdef>
+ <para>A remote directory describes a feature of
+ Lustre where metadata for files in a given directory may be
+ stored on a different MDT than the metadata for the parent
+ directory. Remote directories only became possible with the
+ advent of DNE Phase 1, which arrived in Lustre version
+ 2.4. Remote directories are available to system
+ administrators who wish to provide individual metadata
+ targets for individual workloads.</para>
+ </glossdef>
+ </glossentry>
<glossentry xml:id="replay">
<glossterm>Replay request</glossterm>
<glossdef>
<glossentry xml:id="routing">
<glossterm>Routing</glossterm>
<glossdef>
- <para>LNET routing between different networks and LNDs.</para>
+ <para>LNet routing between different networks and LNDs.</para>
</glossdef>
</glossentry>
<glossentry xml:id="rpc">
</glossdiv>
<glossdiv>
<title>S</title>
- <glossentry xml:id="stride">
+ <glossentry xml:id="stripe">
<glossterm>Stripe</glossterm>
<glossdef>
<para>A contiguous, logical extent of a Lustre file written to a single
of a file visible to user applications.</para>
</glossdef>
</glossentry>
+ <glossentry xml:id="stripeddirectory" condition='l28'>
+ <glossterm>Striped Directory</glossterm>
+ <glossdef>
+ <para>A striped directory is a feature of Lustre
+ software where metadata for files in a given directory are
+ distributed evenly over multiple MDTs. Striped directories
+ are only available in Lustre software version 2.8 or later.
+ An administrator can use a striped directory to increase
+ metadata performance by distributing the metadata requests
+ in a single directory over two or more MDTs.</para>
+ </glossdef>
+ </glossentry>
<glossentry xml:id="stridesize">
<glossterm>Stripe size</glossterm>
<glossdef>
file.</para>
</glossdef>
</glossentry>
- <glossentry xml:id="stripingmetadata">
- <glossterm>Striping metadata</glossterm>
- <glossdef>
- <para>The extended attribute associated with a file that describes how
- its data is distributed over storage objects. See also
- <emphasis role="italic">Default stripe pattern</emphasis>.</para>
- </glossdef>
- </glossentry>
</glossdiv>
<glossdiv>
<title>T</title>
utilization of many OSTs. For more information about wide striping, see
<xref xmlns:xlink="http://www.w3.org/1999/xlink"
- linkend="section_syy_gcl_qk" />.</para>
+ linkend="wide_striping" />.</para>
</glossdef>
</glossentry>
</glossdiv>
git://git.whamcloud.com / doc / manual.git / blobdiff