diff options
| author | NeilBrown <neilb@suse.com> | 2016-11-18 16:16:11 +1100 |
|---|---|---|
| committer | Shaohua Li <shli@fb.com> | 2016-11-22 08:58:17 -0800 |
| commit | 688834e6ae6b21e3d98b5cf2586aa4a9b515c3a0 (patch) | |
| tree | 508a052e94aa8483545417395b5261b86c706587 /include/uapi/linux/raid | |
| parent | 3bddb7f8f264ec58dc86e11ca97341c24f9d38f6 (diff) | |
md/failfast: add failfast flag for md to be used by some personalities.
This patch just adds a 'failfast' per-device flag which can be stored
in v0.90 or v1.x metadata.
The flag is not used yet but the intent is that it can be used for
mirrored (raid1/raid10) arrays where low latency is more important
than keeping all devices on-line.
Setting the flag for a device effectively gives permission for that
device to be marked as Faulty and excluded from the array on the first
error. The underlying driver will be directed not to retry requests
that result in failures. There is a proviso that the device must not
be marked faulty if that would cause the array as a whole to fail, it
may only be marked Faulty if the array remains functional, but is
degraded.
Failures on read requests will cause the device to be marked
as Faulty immediately so that further reads will avoid that
device. No attempt will be made to correct read errors by
over-writing with the correct data.
It is expected that if transient errors, such as cable unplug, are
possible, then something in user-space will revalidate failed
devices and re-add them when they appear to be working again.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'include/uapi/linux/raid')
| -rw-r--r-- | include/uapi/linux/raid/md_p.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h index c3e654c6d518..9930f3e9040f 100644 --- a/include/uapi/linux/raid/md_p.h +++ b/include/uapi/linux/raid/md_p.h @@ -84,6 +84,10 @@ #define MD_DISK_CANDIDATE 5 /* disk is added as spare (local) until confirmed * For clustered enviroments only. */ +#define MD_DISK_FAILFAST 10 /* Send REQ_FAILFAST if there are multiple + * devices available - and don't try to + * correct read errors. + */ #define MD_DISK_WRITEMOSTLY 9 /* disk is "write-mostly" is RAID1 config. * read requests will only be sent here in @@ -265,8 +269,9 @@ struct mdp_superblock_1 { __le32 dev_number; /* permanent identifier of this device - not role in raid */ __le32 cnt_corrected_read; /* number of read errors that were corrected by re-writing */ __u8 device_uuid[16]; /* user-space setable, ignored by kernel */ - __u8 devflags; /* per-device flags. Only one defined...*/ + __u8 devflags; /* per-device flags. Only two defined...*/ #define WriteMostly1 1 /* mask for writemostly flag in above */ +#define FailFast1 2 /* Should avoid retries and fixups and just fail */ /* Bad block log. If there are any bad blocks the feature flag is set. * If offset and size are non-zero, that space is reserved and available */ |