diff options
Diffstat (limited to 'Documentation/device-mapper')
| -rw-r--r-- | Documentation/device-mapper/delay.txt | 3 | ||||
| -rw-r--r-- | Documentation/device-mapper/dm-integrity.txt | 4 | ||||
| -rw-r--r-- | Documentation/device-mapper/dm-raid.txt | 4 | ||||
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 20 | ||||
| -rw-r--r-- | Documentation/device-mapper/writecache.txt | 70 |
5 files changed, 93 insertions, 8 deletions
diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt index 4b1d22a44ce4..6426c45273cb 100644 --- a/Documentation/device-mapper/delay.txt +++ b/Documentation/device-mapper/delay.txt @@ -5,7 +5,8 @@ Device-Mapper's "delay" target delays reads and/or writes and maps them to different devices. Parameters: - <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] + <device> <offset> <delay> [<write_device> <write_offset> <write_delay> + [<flush_device> <flush_offset> <flush_delay>]] With separate write parameters, the first set is only used for reads. Offsets are specified in sectors. diff --git a/Documentation/device-mapper/dm-integrity.txt b/Documentation/device-mapper/dm-integrity.txt index f33e3ade7a09..297251b0d2d5 100644 --- a/Documentation/device-mapper/dm-integrity.txt +++ b/Documentation/device-mapper/dm-integrity.txt @@ -113,6 +113,10 @@ internal_hash:algorithm(:key) (the key is optional) from an upper layer target, such as dm-crypt. The upper layer target should check the validity of the integrity tags. +recalculate + Recalculate the integrity tags automatically. It is only valid + when using internal hash. + journal_crypt:algorithm(:key) (the key is optional) Encrypt the journal using given algorithm to make sure that the attacker can't read the journal. You can use a block cipher here diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt index 390c145f01d7..52a719b49afd 100644 --- a/Documentation/device-mapper/dm-raid.txt +++ b/Documentation/device-mapper/dm-raid.txt @@ -348,3 +348,7 @@ Version History 1.13.1 Fix deadlock caused by early md_stop_writes(). Also fix size an state races. 1.13.2 Fix raid redundancy validation and avoid keeping raid set frozen +1.14.0 Fix reshape race on small devices. Fix stripe adding reshape + deadlock/potential data corruption. Update superblock when + specific devices are requested via rebuild. Fix RAID leg + rebuild errors. diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index 3d01948ea061..883e7ca5f745 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -28,17 +28,18 @@ administrator some freedom, for example to: Status ====== -These targets are very much still in the EXPERIMENTAL state. Please -do not yet rely on them in production. But do experiment and offer us -feedback. Different use cases will have different performance -characteristics, for example due to fragmentation of the data volume. +These targets are considered safe for production use. But different use +cases will have different performance characteristics, for example due +to fragmentation of the data volume. If you find this software is not performing as expected please mail dm-devel@redhat.com with details and we'll try our best to improve things for you. -Userspace tools for checking and repairing the metadata are under -development. +Userspace tools for checking and repairing the metadata have been fully +developed and are available as 'thin_check' and 'thin_repair'. The name +of the package that provides these utilities varies by distribution (on +a Red Hat distribution it is named 'device-mapper-persistent-data'). Cookbook ======== @@ -280,7 +281,7 @@ ii) Status <transaction id> <used metadata blocks>/<total metadata blocks> <used data blocks>/<total data blocks> <held metadata root> ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space - needs_check|- + needs_check|- metadata_low_watermark transaction id: A 64-bit number used by userspace to help synchronise with metadata @@ -327,6 +328,11 @@ ii) Status thin-pool can be made fully operational again. '-' indicates needs_check is not set. + metadata_low_watermark: + Value of metadata low watermark in blocks. The kernel sets this + value internally but userspace needs to know this value to + determine if an event was caused by crossing this threshold. + iii) Messages create_thin <dev id> diff --git a/Documentation/device-mapper/writecache.txt b/Documentation/device-mapper/writecache.txt new file mode 100644 index 000000000000..01532b3008ae --- /dev/null +++ b/Documentation/device-mapper/writecache.txt @@ -0,0 +1,70 @@ +The writecache target caches writes on persistent memory or on SSD. It +doesn't cache reads because reads are supposed to be cached in page cache +in normal RAM. + +When the device is constructed, the first sector should be zeroed or the +first sector should contain valid superblock from previous invocation. + +Constructor parameters: +1. type of the cache device - "p" or "s" + p - persistent memory + s - SSD +2. the underlying device that will be cached +3. the cache device +4. block size (4096 is recommended; the maximum block size is the page + size) +5. the number of optional parameters (the parameters with an argument + count as two) + start_sector n (default: 0) + offset from the start of cache device in 512-byte sectors + high_watermark n (default: 50) + start writeback when the number of used blocks reach this + watermark + low_watermark x (default: 45) + stop writeback when the number of used blocks drops below + this watermark + writeback_jobs n (default: unlimited) + limit the number of blocks that are in flight during + writeback. Setting this value reduces writeback + throughput, but it may improve latency of read requests + autocommit_blocks n (default: 64 for pmem, 65536 for ssd) + when the application writes this amount of blocks without + issuing the FLUSH request, the blocks are automatically + commited + autocommit_time ms (default: 1000) + autocommit time in milliseconds. The data is automatically + commited if this time passes and no FLUSH request is + received + fua (by default on) + applicable only to persistent memory - use the FUA flag + when writing data from persistent memory back to the + underlying device + nofua + applicable only to persistent memory - don't use the FUA + flag when writing back data and send the FLUSH request + afterwards + - some underlying devices perform better with fua, some + with nofua. The user should test it + +Status: +1. error indicator - 0 if there was no error, otherwise error number +2. the number of blocks +3. the number of free blocks +4. the number of blocks under writeback + +Messages: + flush + flush the cache device. The message returns successfully + if the cache device was flushed without an error + flush_on_suspend + flush the cache device on next suspend. Use this message + when you are going to remove the cache device. The proper + sequence for removing the cache device is: + 1. send the "flush_on_suspend" message + 2. load an inactive table with a linear target that maps + to the underlying device + 3. suspend the device + 4. ask for status and verify that there are no errors + 5. resume the device, so that it will use the linear + target + 6. the cache device is now inactive and it can be deleted |