diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-10 13:06:15 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-10 13:06:15 -0700 |
commit | 7426d62871dafbeeed087d609c6469a515c88389 (patch) | |
tree | 7d935f360eeb5e78ba633238a29e9213c291aad7 /Documentation/device-mapper/cache.txt | |
parent | 4d7696f1b05f4aeb586c74868fe3da2731daca4b (diff) | |
parent | 7fff5e8f727285cf54e6aba10f31b196f207b98a (diff) | |
download | op-kernel-dev-7426d62871dafbeeed087d609c6469a515c88389.zip op-kernel-dev-7426d62871dafbeeed087d609c6469a515c88389.tar.gz |
Merge tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device-mapper updates from Mike Snitzer:
"Add the ability to collect I/O statistics on user-defined regions of a
device-mapper device. This dm-stats code required the reintroduction
of a div64_u64_rem() helper, but as a separate method that doesn't
slow down div64_u64() -- especially on 32-bit systems.
Allow the error target to replace request-based DM devices (e.g.
multipath) in addition to bio-based DM devices.
Various other small code fixes and improvements to thin-provisioning,
DM cache and the DM ioctl interface"
* tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm stripe: silence a couple sparse warnings
dm: add statistics support
dm thin: always return -ENOSPC if no_free_space is set
dm ioctl: cleanup error handling in table_load
dm ioctl: increase granularity of type_lock when loading table
dm ioctl: prevent rename to empty name or uuid
dm thin: set pool read-only if breaking_sharing fails block allocation
dm thin: prefix pool error messages with pool device name
dm: allow error target to replace bio-based and request-based targets
math64: New separate div64_u64_rem helper
dm space map: optimise sm_ll_dec and sm_ll_inc
dm btree: prefetch child nodes when walking tree for a dm_btree_del
dm btree: use pop_frame in dm_btree_del to cleanup code
dm cache: eliminate holes in cache structure
dm cache: fix stacking of geometry limits
dm thin: fix stacking of geometry limits
dm thin: add data block size limits to Documentation
dm cache: add data block size limits to code and Documentation
dm cache: document metadata device is exclussive to a cache
dm: stop using WQ_NON_REENTRANT
Diffstat (limited to 'Documentation/device-mapper/cache.txt')
-rw-r--r-- | Documentation/device-mapper/cache.txt | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index e8cdf72..33d45ee 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -50,14 +50,16 @@ other parameters detailed later): which are dirty, and extra hints for use by the policy object. This information could be put on the cache device, but having it separate allows the volume manager to configure it differently, - e.g. as a mirror for extra robustness. + e.g. as a mirror for extra robustness. This metadata device may only + be used by a single cache device. Fixed block size ---------------- The origin is divided up into blocks of a fixed size. This block size is configurable when you first create the cache. Typically we've been -using block sizes of 256k - 1024k. +using block sizes of 256KB - 1024KB. The block size must be between 64 +(32KB) and 2097152 (1GB) and a multiple of 64 (32KB). Having a fixed block size simplifies the target a lot. But it is something of a compromise. For instance, a small part of a block may be |