From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephane Thiell <sthiell@stanford.edu>
Subject: Re: mismatch_cnt > 0 during initial sync?
Date: Tue, 25 Apr 2017 05:14:37 +0000
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I just did some tests and this seems normal if one of the raid disk previou=
sly has some non-zero data.  Perhaps there should be a note about that in m=
d(4) or elsewhere? (sorry if I missed it)

Thanks,

Stephan

> On Apr 24, 2017, at 3:01 PM, Stephane Thiell <sthiell@stanford.edu> wrote=
:
>=20
>=20
> Hi all,
>=20
> Is it normal to get any mismatch_cnt > 0 during the initial sync? I just =
created a few new new raid6 volumes, and one of them is showing an increasi=
ng number of mismatch_cnt during its initial resync. Nothing is visible in =
the console nor after a smart short test (I also started a long test just i=
n case).
>=20
>=20
> $ mdadm --detail /dev/md7
> /dev/md7:
>        Version : 1.2
>  Creation Time : Mon Apr 24 10:07:18 2017
>     Raid Level : raid6
>     Array Size : 62511163904 (59615.29 GiB 64011.43 GB)
>  Used Dev Size : 7813895488 (7451.91 GiB 8001.43 GB)
>   Raid Devices : 10
>  Total Devices : 10
>    Persistence : Superblock is persistent
>=20
>  Intent Bitmap : Internal
>=20
>    Update Time : Mon Apr 24 14:52:12 2017
>          State : clean, resyncing=20
> Active Devices : 10
> Working Devices : 10
> Failed Devices : 0
>  Spare Devices : 0
>=20
>         Layout : left-symmetric
>     Chunk Size : 64K
>=20
>  Resync Status : 24% complete
>=20
>           Name : oak-io1-s2:7  (local to host oak-io1-s2)
>           UUID : 6ece9d71:a97f9497:4612ed73:44dfdc0a
>         Events : 3308
>=20
>    Number   Major   Minor   RaidDevice State
>       0     253       62        0      active sync   /dev/dm-62
>       1     253       63        1      active sync   /dev/dm-63
>       2     253       72        2      active sync   /dev/dm-72
>       3     253       75        3      active sync   /dev/dm-75
>       4     253       89        4      active sync   /dev/dm-89
>       5     253       87        5      active sync   /dev/dm-87
>       6     253      119        6      active sync   /dev/dm-119
>       7     253       97        7      active sync   /dev/dm-97
>       8     253      103        8      active sync   /dev/dm-103
>       9     253      107        9      active sync   /dev/dm-107
>=20
> $ cat /sys/block/md7/md/sync_completed
> 3795284824 / 15627790976
>=20
> $ cat /sys/block/md7/md/mismatch_cnt=20
> 3424
>=20
> versions:
>  mdadm-3.4-14.el7_3.1.x86_64
>  CentOS7 (3.10.0-514.10.2.el7_lustre.x86_64)
>=20
> Thanks!
>=20
> Stephan
> --
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