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| author | Paul Clements <paul.clements@steeleye.com> | 2006-10-03 10:15:49 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-03 17:04:17 +0200 |
| commit | 9b1d1dac181d8c1b9492e05cee660a985d035a06 (patch) | |
| tree | af12b1eaac4e0f7f3528ec26a223faeabed35845 /Documentation/md.txt | |
| parent | [PATCH] md: remove 'working_disks' from raid10 state (diff) | |
| download | linux-9b1d1dac181d8c1b9492e05cee660a985d035a06.tar.xz linux-9b1d1dac181d8c1b9492e05cee660a985d035a06.zip | |
[PATCH] md: new sysfs interface for setting bits in the write-intent-bitmap
Add a new sysfs interface that allows the bitmap of an array to be dirtied.
The interface is write-only, and is used as follows:
echo "1000" > /sys/block/md2/md/bitmap
(dirty the bit for chunk 1000 [offset 0] in the in-memory and on-disk
bitmaps of array md2)
echo "1000-2000" > /sys/block/md1/md/bitmap
(dirty the bits for chunks 1000-2000 in md1's bitmap)
This is useful, for example, in cluster environments where you may need to
combine two disjoint bitmaps into one (following a server failure, after a
secondary server has taken over the array). By combining the bitmaps on
the two servers, a full resync can be avoided (This was discussed on the
list back on March 18, 2005, "[PATCH 1/2] md bitmap bug fixes" thread).
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/md.txt')
| -rw-r--r-- | Documentation/md.txt | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt index 0668f9dc9d29..084ecf4eb2f8 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -410,6 +410,15 @@ also have than sectors, this my be larger than the number of actual errors by a factor of the number of sectors in a page. + bitmap_set_bits + If the array has a write-intent bitmap, then writing to this + attribute can set bits in the bitmap, indicating that a resync + would need to check the corresponding blocks. Either individual + numbers or start-end pairs can be written. Multiple numbers + can be separated by a space. + Note that the numbers are 'bit' numbers, not 'block' numbers. + They should be scaled by the bitmap_chunksize. + 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 |