X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fmd.txt;h=1da9d1b1793f3436b3561a48de7fbcd8c893e74e;hb=d7027458d68b2f1752a28016dcf2ffd0a7e8f567;hp=2202f5dc8ac208381a241bd5fc6b56b73c81ea9a;hpb=f0eef25339f92f7cd4aeea23d9ae97987a5a1e82;p=pandora-kernel.git diff --git a/Documentation/md.txt b/Documentation/md.txt index 2202f5dc8ac2..1da9d1b1793f 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -178,6 +178,21 @@ All md devices contain: The size should be at least PAGE_SIZE (4k) and should be a power of 2. This can only be set while assembling an array + 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. + + 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 + attributes mentioned above (raid_disks, chunk_size, layout) can + potentially have 2 values, an old and a new value. If these + values differ, reading the attribute returns + new (old) + and writing will effect the 'new' value, leaving the 'old' + unchanged. + component_size For arrays with data redundancy (i.e. not raid0, linear, faulty, multipath), all components must be the same size - or at least @@ -193,11 +208,6 @@ All md devices contain: 1.2 (newer format in varying locations) or "none" indicating that the kernel isn't managing metadata at all. - 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 @@ -226,6 +236,11 @@ All md devices contain: writing the word for the desired state, however some states cannot be explicitly set, and some transitions are not allowed. + Select/poll works on this file. All changes except between + active_idle and active (which can be frequent and are not + very interesting) are notified. active->active_idle is + reported if the metadata is externally managed. + clear No devices, no size, no level Writing is equivalent to STOP_ARRAY ioctl @@ -259,29 +274,6 @@ All md devices contain: 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} - however they only apply to the particular array. - If no value has been written to these, of if the word 'system' - is written, then the system-wide value is used. If a value, - in kibibytes-per-second is written, then it is used. - When the files are read, they show the currently active value - followed by "(local)" or "(system)" depending on whether it is - a locally set or system-wide value. - - sync_completed - This shows the number of sectors that have been completed of - whatever the current sync_action is, followed by the number of - sectors in total that could need to be processed. The two - numbers are separated by a '/' thus effectively showing one - value, a fraction of the process that is complete. - - sync_speed - This shows the current actual speed, in K/sec, of the current - sync_action. It is averaged over the last 30 seconds. - - As component devices are added to an md array, they appear in the 'md' directory as new directories named dev-XXX @@ -305,6 +297,10 @@ Each directory contains: writemostly - device will only be subject to read 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. + 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 @@ -314,6 +310,12 @@ Each directory contains: Writing "remove" removes the device from the array. Writing "writemostly" sets the writemostly flag. Writing "-writemostly" clears the writemostly flag. + Writing "blocked" sets the "blocked" flag. + Writing "-blocked" clear the "blocked" flag and allows writes + to complete. + + This file responds to select/poll. Any change to 'faulty' + or 'blocked' causes an event. errors An approximate count of read errors that have been detected on @@ -345,7 +347,7 @@ Each directory contains: for storage of data. This will normally be the same as the component_size. This can be written while assembling an array. If a value less than the current component_size is - written, component_size will be reduced to this value. + written, it will be rejected. An active md device will also contain and entry for each active device @@ -394,6 +396,19 @@ also have 'check' and 'repair' will start the appropriate process providing the current state is 'idle'. + This file responds to select/poll. Any important change in the value + triggers a poll event. Sometimes the value will briefly be + "recover" if a recovery seems to be needed, but cannot be + achieved. In that case, the transition to "recover" isn't + notified, but the transition away is. + + degraded + This contains a count of the number of devices by which the + arrays is degraded. So an optimal array with 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. + mismatch_count When performing 'check' and 'repair', and possibly when performing 'resync', md will count the number of errors that are @@ -412,6 +427,45 @@ also have Note that the numbers are 'bit' numbers, not 'block' numbers. They should be scaled by the bitmap_chunksize. + sync_speed_min + sync_speed_max + This are similar to /proc/sys/dev/raid/speed_limit_{min,max} + however they only apply to the particular array. + If no value has been written to these, of if the word 'system' + is written, then the system-wide value is used. If a value, + in kibibytes-per-second is written, then it is used. + When the files are read, they show the currently active value + followed by "(local)" or "(system)" depending on whether it is + a locally set or system-wide value. + + sync_completed + This shows the number of sectors that have been completed of + whatever the current sync_action is, followed by the number of + sectors in total that could need to be processed. The two + numbers are separated by a '/' thus effectively showing one + value, a fraction of the process that is complete. + A 'select' on this attribute will return when resync completes, + 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. + + suspend_lo + suspend_hi + The two values, given as numbers of sectors, indicate a range + within the array where IO will be blocked. This is currently + only supported for raid4/5/6. + + Each active md device may also have attributes specific to the personality module that manages it. These are specific to the implementation of the module and could @@ -424,3 +478,9 @@ These currently include there are upper and lower limits (32768, 16). Default is 128. strip_cache_active (currently raid5 only) number of active entries in the stripe cache + preread_bypass_threshold (currently raid5 only) + number of times a stripe requiring preread will be bypassed by + a stripe that does not require preread. For fairness defaults + to 1. Setting this to 0 disables bypass accounting and + requires preread stripes to wait until all full-width stripe- + writes are complete. Valid values are 0 to stripe_cache_size.