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Diffstat (limited to 'Documentation/device-mapper/dm-raid.txt')
| -rw-r--r-- | Documentation/device-mapper/dm-raid.txt | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt index 5e3786fd9ea7..cd2cb2fc85ea 100644 --- a/Documentation/device-mapper/dm-raid.txt +++ b/Documentation/device-mapper/dm-raid.txt @@ -161,6 +161,15 @@ The target is named "raid" and it accepts the following parameters: the RAID type (i.e. the allocation algorithm) as well, e.g. changing from raid5_ls to raid5_n. + [journal_dev <dev>] + This option adds a journal device to raid4/5/6 raid sets and + uses it to close the 'write hole' caused by the non-atomic updates + to the component devices which can cause data loss during recovery. + The journal device is used as writethrough thus causing writes to + be throttled versus non-journaled raid4/5/6 sets. + Takeover/reshape is not possible with a raid4/5/6 journal device; + it has to be deconfigured before requesting these. + <#raid_devs>: The number of devices composing the array. Each device consists of two entries. The first is the device containing the metadata (if any); the second is the one containing the @@ -245,6 +254,9 @@ recovery. Here is a fuller description of the individual fields: <data_offset> The current data offset to the start of the user data on each component device of a raid set (see the respective raid parameter to support out-of-place reshaping). + <journal_char> 'A' - active raid4/5/6 journal device. + 'D' - dead journal device. + '-' - no journal device. Message Interface @@ -307,10 +319,15 @@ Version History 1.5.2 'mismatch_cnt' is zero unless [last_]sync_action is "check". 1.6.0 Add discard support (and devices_handle_discard_safely module param). 1.7.0 Add support for MD RAID0 mappings. -1.8.0 Explictely check for compatible flags in the superblock metadata +1.8.0 Explicitly check for compatible flags in the superblock metadata and reject to start the raid set if any are set by a newer target version, thus avoiding data corruption on a raid set with a reshape in progress. 1.9.0 Add support for RAID level takeover/reshape/region size and set size reduction. 1.9.1 Fix activation of existing RAID 4/10 mapped devices +1.9.2 Don't emit '- -' on the status table line in case the constructor + fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and + 'D' on the status line. If '- -' is passed into the constructor, emit + '- -' on the table line and '-' as the status line health character. +1.10.0 Add support for raid4/5/6 journal device |