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Diffstat (limited to 'Documentation/md.txt')
| -rw-r--r-- | Documentation/md.txt | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt index 03a13c462cf2..0668f9dc9d29 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -200,6 +200,17 @@ All md devices contain: This can be written only while the array is being assembled, not after it is started. + layout + The "layout" for the array for the particular level. This is + simply a number that is interpretted differently by different + levels. It can be written while assembling an array. + + resync_start + The point at which resync should start. If no resync is needed, + this will be a very large number. At array creation it will + default to 0, though starting the array as 'clean' will + set it much larger. + new_dev This file can be written but not read. The value written should be a block device number as major:minor. e.g. 8:0 @@ -207,6 +218,54 @@ All md devices contain: available. It will then appear at md/dev-XXX (depending on the name of the device) and further configuration is then possible. + safe_mode_delay + When an md array has seen no write requests for a certain period + of time, it will be marked as 'clean'. When another write + request arrive, the array is marked as 'dirty' before the write + commenses. This is known as 'safe_mode'. + The 'certain period' is controlled by this file which stores the + period as a number of seconds. The default is 200msec (0.200). + Writing a value of 0 disables safemode. + + array_state + This file contains a single word which describes the current + state of the array. In many cases, the state can be set by + writing the word for the desired state, however some states + cannot be explicitly set, and some transitions are not allowed. + + clear + No devices, no size, no level + Writing is equivalent to STOP_ARRAY ioctl + inactive + May have some settings, but array is not active + all IO results in error + When written, doesn't tear down array, but just stops it + suspended (not supported yet) + All IO requests will block. The array can be reconfigured. + Writing this, if accepted, will block until array is quiessent + readonly + no resync can happen. no superblocks get written. + write requests fail + read-auto + like readonly, but behaves like 'clean' on a write request. + + clean - no pending writes, but otherwise active. + When written to inactive array, starts without resync + If a write request arrives then + if metadata is known, mark 'dirty' and switch to 'active'. + if not known, block and switch to write-pending + If written to an active array that has pending writes, then fails. + active + fully active: IO and resync can be happening. + When written to inactive array, starts with resync + + write-pending + clean, but writes are blocked waiting for 'active' to be written. + + active-idle + like active, but no writes have been seen for a while (safe_mode_delay). + + sync_speed_min sync_speed_max This are similar to /proc/sys/dev/raid/speed_limit_{min,max} @@ -250,10 +309,18 @@ Each directory contains: faulty - device has been kicked from active use due to a detected fault 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. + This applies only to raid1 arrays. spare - device is working, but not a full member. This includes spares that are in the process of being recoverred to This list make grow in future. + This can be written to. + Writing "faulty" simulates a failure on the device. + Writing "remove" removes the device from the array. + Writing "writemostly" sets the writemostly flag. + Writing "-writemostly" clears the writemostly flag. errors An approximate count of read errors that have been detected on |