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
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
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
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
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
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
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
'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
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
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.
git.openpandora.org / pandora-kernel.git / blobdiff