Re: [linux-lvm] LVM commands extremely slow during raid check/resync

[Larkin Lowrey <llowrey@nuclearwinter.com>]

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I'll try the patches when I get a chance. In the mean time, I've
provided the info you requested as well as a "profiled" run of "lvcreate
-vvvv" attached as lvcreate.txt.gz. The file is pipe delimited with the
2nd field being the delta timestamps in ms between the current line and
the prior line. When that lvcreate was run all arrays, except md0, were
doing a check.

# pvs -a
  PV               VG   Fmt  Attr PSize   PFree
  /dev/Raid/Boot             ---       0       0
  /dev/Raid/Root             ---       0       0
  /dev/Raid/Swap             ---       0       0
  /dev/Raid/Videos           ---       0       0
  /dev/md0         Raid lvm2 a--  496.00m      0
  /dev/md1         Raid lvm2 a--    2.03t 100.00g
  /dev/md10        Raid lvm2 a--    1.46t      0
  /dev/md2         Raid lvm2 a--    9.10t      0

# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md10 : active raid5 sdt1[6] sds1[5] sdm1[0] sdn1[1] sdl1[2] sdk1[4]
      1562845120 blocks super 1.2 level 5, 64k chunk, algorithm 2 [6/6]
[UUUUUU]

md2 : active raid5 sdr1[5] sdo1[4] sdq1[0] sdp1[3] sdg1[2] sdh1[1]
      9767559680 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]

md0 : active raid6 sde1[4] sdc1[2] sdf1[5] sda1[1] sdb1[0] sdd1[3]
      509952 blocks super 1.2 level 6, 512k chunk, algorithm 2 [6/6]
[UUUUUU]

md1 : active raid5 sdb2[10] sde2[1] sdc2[3] sda2[9] sdd2[0] sdi2[6]
sdf2[4] sdj2[8]
      2180641792 blocks super 1.2 level 5, 64k chunk, algorithm 2 [8/8]
[UUUUUUUU]

unused devices: <none>


--Larkin

On 3/27/2012 9:34 AM, Zdenek Kabelac wrote:
> Dne 27.3.2012 01:51, Larkin Lowrey napsal(a):
>> That helped bring the lvcreate time down from 2min to 1min so that's an
>> improvement.  Thank you.
>>
>> The source of the remaining slowdown is the writing of metadata to my 4
>> PVs. The writes are small and the arrays are all raid5 so each metadata
>> write is also requiring a read. I'm still at a loss for why this was not
>> a problem when running F15 but the filter is a workable solution for me
>> so I'll leave it alone.
>>
>
> Could you please attach attach output of 'lvs -a' and eventually your md array
> setup.
>
> Ideally open regular bugzilla for f16.
>
> Zdenek
>
>
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