diff options
Diffstat (limited to 'Documentation/md.txt')
| -rw-r--r-- | Documentation/md.txt | 88 |
1 files changed, 64 insertions, 24 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt index a81c7b4790f..f925666e434 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -119,7 +119,7 @@ device to add. The array is started with the RUN_ARRAY ioctl. Once started, new devices can be added. They should have an -appropriate superblock written to them, and then passed be in with +appropriate superblock written to them, and then be passed in with ADD_NEW_DISK. Devices that have failed or are not yet active can be detached from an @@ -131,7 +131,7 @@ Specific Rules that apply to format-0 super block arrays, and ------------------------------------------------------------- An array can be 'created' by describing the array (level, chunksize -etc) in a SET_ARRAY_INFO ioctl. This must has major_version==0 and +etc) in a SET_ARRAY_INFO ioctl. This must have major_version==0 and raid_disks != 0. Then uninitialized devices can be added with ADD_NEW_DISK. The @@ -357,21 +357,30 @@ Each directory contains: written to, that device. state - A file recording the current state of the device in the array + A file recording the current state of the device in the array which can be a comma separated list of faulty - device has been kicked from active use due to - a detected fault + a detected fault, or it has unacknowledged bad + blocks in_sync - device is a fully in-sync member of the array writemostly - device will only be subject to read - requests if there are no other options. + requests if there are no other options. This applies only to raid1 arrays. - blocked - device has failed, metadata is "external", - and the failure hasn't been acknowledged yet. + blocked - device has failed, and the failure hasn't been + acknowledged yet by the metadata handler. Writes that would write to this device if it were not faulty are blocked. spare - device is working, but not a full member. This includes spares that are in the process of being recovered to + write_error - device has ever seen a write error. + want_replacement - device is (mostly) working but probably + should be replaced, either due to errors or + due to user request. + replacement - device is a replacement for another active + device with same raid_disk. + + This list may grow in future. This can be written to. Writing "faulty" simulates a failure on the device. @@ -379,9 +388,18 @@ Each directory contains: Writing "writemostly" sets the writemostly flag. Writing "-writemostly" clears the writemostly flag. Writing "blocked" sets the "blocked" flag. - Writing "-blocked" clears the "blocked" flag and allows writes - to complete. + Writing "-blocked" clears the "blocked" flags and allows writes + to complete and possibly simulates an error. Writing "in_sync" sets the in_sync flag. + Writing "write_error" sets writeerrorseen flag. + Writing "-write_error" clears writeerrorseen flag. + Writing "want_replacement" is allowed at any time except to a + replacement device or a spare. It sets the flag. + Writing "-want_replacement" is allowed at any time. It clears + the flag. + Writing "replacement" or "-replacement" is only allowed before + starting the array. It sets or clears the flag. + This file responds to select/poll. Any change to 'faulty' or 'blocked' causes an event. @@ -408,7 +426,7 @@ Each directory contains: offset This gives the location in the device (in sectors from the start) where data from the array will be stored. Any part of - the device before this offset us not touched, unless it is + the device before this offset is not touched, unless it is used for storing metadata (Formats 1.1 and 1.2). size @@ -419,11 +437,10 @@ Each directory contains: written, it will be rejected. recovery_start - When the device is not 'in_sync', this records the number of sectors from the start of the device which are known to be correct. This is normally zero, but during a recovery - operation is will steadily increase, and if the recovery is + operation it will steadily increase, and if the recovery is interrupted, restoring this value can cause recovery to avoid repeating the earlier blocks. With v1.x metadata, this value is saved and restored automatically. @@ -435,9 +452,23 @@ Each directory contains: Setting this to 'none' is equivalent to setting 'in_sync'. Setting to any other value also clears the 'in_sync' flag. + bad_blocks + This gives the list of all known bad blocks in the form of + start address and length (in sectors respectively). If output + is too big to fit in a page, it will be truncated. Writing + "sector length" to this file adds new acknowledged (i.e. + recorded to disk safely) bad blocks. + unacknowledged_bad_blocks + This gives the list of known-but-not-yet-saved-to-disk bad + blocks in the same form of 'bad_blocks'. If output is too big + to fit in a page, it will be truncated. Writing to this file + adds bad blocks without acknowledging them. This is largely + for testing. -An active md device will also contain and entry for each active device + + +An active md device will also contain an entry for each active device in the array. These are named rdNN @@ -451,7 +482,7 @@ will show 'in_sync' on every line. -Active md devices for levels that support data redundancy (1,4,5,6) +Active md devices for levels that support data redundancy (1,4,5,6,10) also have sync_action @@ -463,7 +494,7 @@ also have failed/missing device idle - nothing is happening check - A full check of redundancy was requested and is - happening. This reads all block and checks + happening. This reads all blocks and checks them. A repair may also happen for some raid levels. repair - A full check and repair is happening. This is @@ -491,7 +522,7 @@ also have degraded This contains a count of the number of devices by which the - arrays is degraded. So an optimal array with show '0'. A + arrays is degraded. So an optimal array will show '0'. A single failed/missing drive will show '1', etc. This file responds to select/poll, any increase or decrease in the count of missing devices will trigger an event. @@ -502,7 +533,7 @@ also have found. The count in 'mismatch_cnt' is the number of sectors that were re-written, or (for 'check') would have been re-written. As most raid levels work in units of pages rather - than sectors, this my be larger than the number of actual errors + than sectors, this may be larger than the number of actual errors by a factor of the number of sectors in a page. bitmap_set_bits @@ -535,13 +566,6 @@ also have when it reaches the current sync_max (below) and possibly at other times. - sync_max - This is a number of sectors at which point a resync/recovery - process will pause. When a resync is active, the value can - only ever be increased, never decreased. The value of 'max' - effectively disables the limit. - - sync_speed This shows the current actual speed, in K/sec, of the current sync_action. It is averaged over the last 30 seconds. @@ -552,6 +576,22 @@ also have within the array where IO will be blocked. This is currently only supported for raid4/5/6. + sync_min + sync_max + The two values, given as numbers of sectors, indicate a range + within the array where 'check'/'repair' will operate. Must be + a multiple of chunk_size. When it reaches "sync_max" it will + pause, rather than complete. + You can use 'select' or 'poll' on "sync_completed" to wait for + that number to reach sync_max. Then you can either increase + "sync_max", or can write 'idle' to "sync_action". + + The value of 'max' for "sync_max" effectively disables the limit. + When a resync is active, the value can only ever be increased, + never decreased. + The value of '0' is the minimum for "sync_min". + + Each active md device may also have attributes specific to the personality module that manages it. |