5 An 'obd_statfs' structure conveys file-system-wide information for the
6 back-end file system of a given target (MDT or OST).
33 Most of the fields correspond directly to the 'struct statfs' fields
34 returned by a 'statfs()' system call and have the same meaning. The
35 values are for the back-end storage of the target in question (MDT or
38 Teh 'os_type' field gives the type of the target's back-end file
41 .Back-end file types ('os_type') for Lustre targets
45 | EXT?_SUPER_MAGIC (ldiskfs) | 0xEF53
46 | ZFS_SUPER_MAGIC | 0x2fc12fc1
49 The 'os_blocks' field is the total number of blocks in the target, in
52 The 'os_bfree' field is the number of blocks not currently in use.
54 The 'os_bavail' is the number of blocks available to be allocated to
57 The 'os_files' field is the total number of files on the target, both
58 allocated and free. For some OSD types this is a static number, and
59 for others this is dynamic based on os_ffree and the amount of free
62 The 'os_ffree' field is the current number of files that could be
63 created based on current usage. For some OSD types this is a function
64 of the free space in the device and may increase or decrease as free
67 The 'os_fsid' is intended to be the target backing device UUID in
68 ASCII format. The current osd-ldiskfs and osd-zfs implementations
71 The 'os_bsize' field is the block size in bytes. This is for computing
72 the total, free, and available space in combination with os_blocks,
73 os_bfree, and os_bavail respectively. It does not necessarily
74 represent the minimum or optimal IO size.
76 The 'os_namelen' field gives the maximum name length for files on the
79 The 'os_maxbytes' field is the maximum size of a single object
80 (i.e. the maximum byte offset that can be written to). This is the
81 same value as the 'ocd_maxbytes' field of the 'obd_connect_data'
84 The 'os_state' field encodes the status of the underlying back-end
85 file system. It can be:
87 .Back-end file system state
90 | os_state flag | value
91 | OS_STATE_DEGRADED | 0x1
92 | OS_STATE_READONLY | 0x2
95 In normal operation the 'os_state' value is returned as 0x0. If the
96 back-end file system has a RAID configuration that is degraded or
97 rebuilding the state is returned with the OS_STATE_DEGRADED (0x1) flag
98 set. If the file system has been set to read-only, for whatever
99 reason, then the state is returned with the OS_STATE_READONLY (0x2)
100 flag set, for example if it was explicitly mounted read-only, or
101 corruption has been detected at runtime in the backing filesystem.
103 The 'os_fprecreated' field counts the number of pre-created objects
104 available on an OST. The 'os_fprecreated' value counts as "used"
105 inodes, so it reduces 'os_ffree'. Lustre places a hard limit of
106 2*OST_MAX_PRECREATE (2*20000) on the number of precreates it will
107 allow for an OST. There are currently no precreated objects on an MDT
108 so it is just 0 in that case.