diff options
Diffstat (limited to 'Documentation/admin-guide/md.rst')
| -rw-r--r-- | Documentation/admin-guide/md.rst | 103 |
1 files changed, 78 insertions, 25 deletions
diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst index 84de718f24a4..dc7eab191caa 100644 --- a/Documentation/admin-guide/md.rst +++ b/Documentation/admin-guide/md.rst @@ -5,7 +5,7 @@ Boot time assembly of RAID arrays --------------------------------- Tools that manage md devices can be found at - http://www.kernel.org/pub/linux/utils/raid/ + https://www.kernel.org/pub/linux/utils/raid/ You can boot with your md device with the following kernel command @@ -221,7 +221,7 @@ All md devices contain: layout The ``layout`` for the array for the particular level. This is - simply a number that is interpretted differently by different + simply a number that is interpreted differently by different levels. It can be written while assembling an array. array_size @@ -238,6 +238,16 @@ All md devices contain: the number of devices in a raid4/5/6, or to support external metadata formats which mandate such clipping. + logical_block_size + Configure the array's logical block size in bytes. This attribute + is only supported for 1.x meta. Write the value before starting + array. The final array LBS uses the maximum between this + configuration and LBS of all combined devices. Note that + LBS cannot exceed PAGE_SIZE before RAID supports folio. + WARNING: Arrays created on new kernel cannot be assembled at old + kernel due to padding check, Set module parameter 'check_new_feature' + to false to bypass, but data loss may occur. + reshape_position This is either ``none`` or a sector number within the devices of the array where ``reshape`` is up to. If this is set, the three @@ -317,7 +327,7 @@ All md devices contain: suspended (not supported yet) All IO requests will block. The array can be reconfigured. - Writing this, if accepted, will block until array is quiessent + Writing this, if accepted, will block until array is quiescent readonly no resync can happen. no superblocks get written. @@ -347,6 +357,54 @@ All md devices contain: active-idle like active, but no writes have been seen for a while (safe_mode_delay). + consistency_policy + This indicates how the array maintains consistency in case of unexpected + shutdown. It can be: + + none + Array has no redundancy information, e.g. raid0, linear. + + resync + Full resync is performed and all redundancy is regenerated when the + array is started after unclean shutdown. + + bitmap + Resync assisted by a write-intent bitmap. + + journal + For raid4/5/6, journal device is used to log transactions and replay + after unclean shutdown. + + ppl + For raid5 only, Partial Parity Log is used to close the write hole and + eliminate resync. + + The accepted values when writing to this file are ``ppl`` and ``resync``, + used to enable and disable PPL. + + uuid + This indicates the UUID of the array in the following format: + xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx + + bitmap_type + [RW] When read, this file will display the current and available + bitmap for this array. The currently active bitmap will be enclosed + in [] brackets. Writing an bitmap name or ID to this file will switch + control of this array to that new bitmap. Note that writing a new + bitmap for created array is forbidden. + + none + No bitmap + bitmap + The default internal bitmap + llbitmap + The lockless internal bitmap + +If bitmap_type is not none, then additional bitmap attributes bitmap/xxx or +llbitmap/xxx will be created after md device KOBJ_CHANGE event. + +If bitmap_type is bitmap, then the md device will also contain: + bitmap/location This indicates where the write-intent bitmap for the array is stored. @@ -401,31 +459,23 @@ All md devices contain: once the array becomes non-degraded, and this fact has been recorded in the metadata. - consistency_policy - This indicates how the array maintains consistency in case of unexpected - shutdown. It can be: +If bitmap_type is llbitmap, then the md device will also contain: - none - Array has no redundancy information, e.g. raid0, linear. + llbitmap/bits + This is read-only, show status of bitmap bits, the number of each + value. - resync - Full resync is performed and all redundancy is regenerated when the - array is started after unclean shutdown. + llbitmap/metadata + This is read-only, show bitmap metadata, include chunksize, chunkshift, + chunks, offset and daemon_sleep. - bitmap - Resync assisted by a write-intent bitmap. - - journal - For raid4/5/6, journal device is used to log transactions and replay - after unclean shutdown. - - ppl - For raid5 only, Partial Parity Log is used to close the write hole and - eliminate resync. - - The accepted values when writing to this file are ``ppl`` and ``resync``, - used to enable and disable PPL. + llbitmap/daemon_sleep + This is read-write, time in seconds that daemon function will be + triggered to clear dirty bits. + llbitmap/barrier_idle + This is read-write, time in seconds that page barrier will be idled, + means dirty bits in the page will be cleared. As component devices are added to an md array, they appear in the ``md`` directory as new directories named:: @@ -754,5 +804,8 @@ These currently include: journal_mode (currently raid5 only) The cache mode for raid5. raid5 could include an extra disk for - caching. The mode can be "write-throuth" and "write-back". The + caching. The mode can be "write-through" or "write-back". The default is "write-through". + + ppl_write_hint + NVMe stream ID to be set for each PPL write request. |