Thomas Rosenstein <thomas.rosenstein@xxxxxxxxxxxxxxxx> 于2020年10月22日周四 下午12:28写道：
>
> Hello,
>
> I'm trying todo something interesting, the structure looks like this:
>
> xfs
> - mdraid
> - multipath (with no_path_queue = fail)
> - iscsi path 1
> - iscsi path 2
> - multipath (with no_path_queue = fail)
> - iscsi path 1
> - iscsi path 2
>
> During normal operation everything looks good, once a path fails (i.e.
> iscsi target is removed), the array goes to degraded, if the path comes
> back nothing happens.
>
> Q1) Can I enable auto recovery for failed devices?
>
> If the device is readded manually (or by software) everything resyncs
> and it works again. As all should be.
>
> If BOTH devices fail at the same time (worst case scenario) it gets
> wonky. I would expect a total hang (as with iscsi, and multipath
> queue_no_path)
>
> 1) XFS reports Input/Output error
> 2) dmesg has logs like:
>
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41472, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41473, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41474, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41475, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41476, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41477, async page read
> [Thu Oct 22 09:25:28 2020] Buffer I/O error on dev md127, logical block
> 41478, async page read
>
> 3) mdadm --detail /dev/md127 shows:
>
> /dev/md127:
> Version : 1.2
> Creation Time : Wed Oct 21 17:25:22 2020
> Raid Level : raid1
> Array Size : 96640 (94.38 MiB 98.96 MB)
> Used Dev Size : 96640 (94.38 MiB 98.96 MB)
> Raid Devices : 2
> Total Devices : 2
> Persistence : Superblock is persistent
>
> Update Time : Thu Oct 22 09:23:35 2020
> State : clean, degraded
> Active Devices : 1
> Working Devices : 1
> Failed Devices : 1
> Spare Devices : 0
>
> Consistency Policy : resync
>
> Name : v-b08c6663-7296-4c66-9faf-ac687
> UUID : cc282a5c:59a499b3:682f5e6f:36f9c490
> Events : 122
>
> Number Major Minor RaidDevice State
> 0 253 2 0 active sync /dev/dm-2
> - 0 0 1 removed
>
> 1 253 3 - faulty /dev/dm-
>
> 4) I can read from /dev/md127, but only however much is in the buffer
> (see above dmesg logs)
>
>
> In my opinion this should happen, or at least should be configurable.
> I expect:
> 1) XFS hangs indefinitly (like multipath queue_no_path)
> 2) mdadm shows FAULTED as State
>
> Q2) Can this be configured in any way?
you can enable the last device to fail
9a567843f7ce ("md: allow last device to be forcibly removed from RAID1/RAID10.")
>
> After BOTH paths are recovered, nothing works anymore, and the raid
> doesn't recover automatically.
> Only a complete unmount and stop followed by an assemble and mount makes
> the raid function again.
>
> Q3) Is that expected behavior?
>
> Thanks
> Thomas Rosenstein
