Linux 3.3.1 resync speed

Linux 3.3.1 resync speed

[Mathias Burén]

Hi mailing list,

On my old

model name	: Intel(R) Atom(TM) CPU  330   @ 1.60GHz

I'm currently seeing a resync speed of around 200MB/s!

~ $ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sdg1[0] sde1[7] sdh1[8] sdf1[5] sdc1[3] sdd1[4] sdb1[9]
      9751756800 blocks super 1.2 level 6, 64k chunk, algorithm 2
[7/7] [UUUUUUU]
      [======>..............]  check = 32.6% (636923520/1950351360)
finish=111.2min speed=196740K/sec

unused devices: <none>

This ia almost 10 times higher than what I used to see on 3.2 and
earlier. What's that about? The array is a 7 drive RAID6:

$ sudo mdadm -D /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Tue Oct 19 08:58:41 2010
     Raid Level : raid6
     Array Size : 9751756800 (9300.00 GiB 9985.80 GB)
  Used Dev Size : 1950351360 (1860.00 GiB 1997.16 GB)
   Raid Devices : 7
  Total Devices : 7
    Persistence : Superblock is persistent

    Update Time : Mon Apr  2 22:18:14 2012
          State : clean, checking
 Active Devices : 7
Working Devices : 7
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

   Check Status : 32% complete

           Name : ion:0  (local to host ion)
           UUID : e6595c64:b3ae90b3:f01133ac:3f402d20
         Events : 6773811

    Number   Major   Minor   RaidDevice State
       0       8       97        0      active sync   /dev/sdg1
       9       8       17        1      active sync   /dev/sdb1
       4       8       49        2      active sync   /dev/sdd1
       3       8       33        3      active sync   /dev/sdc1
       5       8       81        4      active sync   /dev/sdf1
       8       8      113        5      active sync   /dev/sdh1
       7       8       65        6      active sync   /dev/sde1

Best regards,
Mathias

Re: Linux 3.3.1 resync speed

[Mathias Burén]

On 2 April 2012 22:21, Mathias Burén <mathias.buren@gmail.com> wrote:
> Hi mailing list,
>
> On my old
>
> model name      : Intel(R) Atom(TM) CPU  330   @ 1.60GHz
>
> I'm currently seeing a resync speed of around 200MB/s!
>
> ~ $ cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md0 : active raid6 sdg1[0] sde1[7] sdh1[8] sdf1[5] sdc1[3] sdd1[4] sdb1[9]
>      9751756800 blocks super 1.2 level 6, 64k chunk, algorithm 2
> [7/7] [UUUUUUU]
>      [======>..............]  check = 32.6% (636923520/1950351360)
> finish=111.2min speed=196740K/sec
>
> unused devices: <none>
>
> This ia almost 10 times higher than what I used to see on 3.2 and
> earlier. What's that about? The array is a 7 drive RAID6:
>
> $ sudo mdadm -D /dev/md0
> /dev/md0:
>        Version : 1.2
>  Creation Time : Tue Oct 19 08:58:41 2010
>     Raid Level : raid6
>     Array Size : 9751756800 (9300.00 GiB 9985.80 GB)
>  Used Dev Size : 1950351360 (1860.00 GiB 1997.16 GB)
>   Raid Devices : 7
>  Total Devices : 7
>    Persistence : Superblock is persistent
>
>    Update Time : Mon Apr  2 22:18:14 2012
>          State : clean, checking
>  Active Devices : 7
> Working Devices : 7
>  Failed Devices : 0
>  Spare Devices : 0
>
>         Layout : left-symmetric
>     Chunk Size : 64K
>
>   Check Status : 32% complete
>
>           Name : ion:0  (local to host ion)
>           UUID : e6595c64:b3ae90b3:f01133ac:3f402d20
>         Events : 6773811
>
>    Number   Major   Minor   RaidDevice State
>       0       8       97        0      active sync   /dev/sdg1
>       9       8       17        1      active sync   /dev/sdb1
>       4       8       49        2      active sync   /dev/sdd1
>       3       8       33        3      active sync   /dev/sdc1
>       5       8       81        4      active sync   /dev/sdf1
>       8       8      113        5      active sync   /dev/sdh1
>       7       8       65        6      active sync   /dev/sde1
>
> Best regards,
> Mathias

It was actually capped at 200000 KB/s in
/sys/block/md0/md/sync_speed_max . I raised that by a factor of 100,
and I am now seeing:

 $ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sdg1[0] sde1[7] sdh1[8] sdf1[5] sdc1[3] sdd1[4] sdb1[9]
      9751756800 blocks super 1.2 level 6, 64k chunk, algorithm 2
[7/7] [UUUUUUU]
      [======>..............]  check = 34.8% (679312336/1950351360)
finish=70.2min speed=301438K/sec

unused devices: <none>

I'm not complaining, just very surprised and I'm wondering if
everything is OK. Usually a check takes around 20-24 hours.

Mathias
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Re: Linux 3.3.1 resync speed

[Larkin Lowrey]

This is a known issue and a patch has been submitted. I'm not sure when
it is scheduled to appear in the kernel.

There will be no actual disk I/O during the raid check and the array
will not actually be checked.

--Larkin

On 4/2/2012 4:21 PM, Mathias Burén wrote:
> Hi mailing list,
>
> On my old
>
> model name	: Intel(R) Atom(TM) CPU  330   @ 1.60GHz
>
> I'm currently seeing a resync speed of around 200MB/s!
>
> ~ $ cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md0 : active raid6 sdg1[0] sde1[7] sdh1[8] sdf1[5] sdc1[3] sdd1[4] sdb1[9]
>       9751756800 blocks super 1.2 level 6, 64k chunk, algorithm 2
> [7/7] [UUUUUUU]
>       [======>..............]  check = 32.6% (636923520/1950351360)
> finish=111.2min speed=196740K/sec
>
> unused devices: <none>
>
> This ia almost 10 times higher than what I used to see on 3.2 and
> earlier. What's that about? The array is a 7 drive RAID6:
>
> $ sudo mdadm -D /dev/md0
> /dev/md0:
>         Version : 1.2
>   Creation Time : Tue Oct 19 08:58:41 2010
>      Raid Level : raid6
>      Array Size : 9751756800 (9300.00 GiB 9985.80 GB)
>   Used Dev Size : 1950351360 (1860.00 GiB 1997.16 GB)
>    Raid Devices : 7
>   Total Devices : 7
>     Persistence : Superblock is persistent
>
>     Update Time : Mon Apr  2 22:18:14 2012
>           State : clean, checking
>  Active Devices : 7
> Working Devices : 7
>  Failed Devices : 0
>   Spare Devices : 0
>
>          Layout : left-symmetric
>      Chunk Size : 64K
>
>    Check Status : 32% complete
>
>            Name : ion:0  (local to host ion)
>            UUID : e6595c64:b3ae90b3:f01133ac:3f402d20
>          Events : 6773811
>
>     Number   Major   Minor   RaidDevice State
>        0       8       97        0      active sync   /dev/sdg1
>        9       8       17        1      active sync   /dev/sdb1
>        4       8       49        2      active sync   /dev/sdd1
>        3       8       33        3      active sync   /dev/sdc1
>        5       8       81        4      active sync   /dev/sdf1
>        8       8      113        5      active sync   /dev/sdh1
>        7       8       65        6      active sync   /dev/sde1
>
> Best regards,
> Mathias
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
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Re: Linux 3.3.1 resync speed

[Mathias Burén]

On 2 April 2012 22:28, Larkin Lowrey <llowrey@nuclearwinter.com> wrote:
> This is a known issue and a patch has been submitted. I'm not sure when
> it is scheduled to appear in the kernel.
>
> There will be no actual disk I/O during the raid check and the array
> will not actually be checked.
>
> --Larkin
>

Ok, thanks for letting me know. I thought it looked too good to be
true. I'm actually observing this on 3.3.0, not 3.3.1 as I originally
reported.

Mathias