* "Rebuild" speed on a forced resync
@ 2005-01-11 9:47 Brad Campbell
2005-01-12 0:33 ` Neil Brown
2005-01-12 0:48 ` Guy
0 siblings, 2 replies; 5+ messages in thread
From: Brad Campbell @ 2005-01-11 9:47 UTC (permalink / raw)
To: RAID Linux
G'day all,
Just started my big raid using mdadm --update resync to ensure the parity blocks are A-OK after a
kernel panic, and I have been monitoring my Disk IO with
iostat -k 5
Now this is an average for a 5 second period.
I note I'm seeing about 12,456 Kilobytes/sec from each drive, but a cat /proc mdstat is giving me
6716 Kilobytes/sec. Given I'm doing a read consistency check I would expect an mdstat speed 9/10ths
of my bulk per-drive read speed. (This array is sda -> sdj)
Am I missing something really obvious?
Kernel 2.6.10-bk10
Regards,
Brad
avg-cpu: %user %nice %sys %iowait %idle
39.18 0.00 60.82 0.00 0.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 97.76 12465.67 0.00 33408 0
sdb 97.76 12465.67 0.00 33408 0
sdc 97.76 12465.67 0.00 33408 0
sdd 97.76 12465.67 0.00 33408 0
sde 97.76 12465.67 0.00 33408 0
sdf 98.51 12465.67 0.00 33408 0
sdg 98.51 12465.67 0.00 33408 0
sdh 98.88 12465.67 0.00 33408 0
sdi 107.09 12465.67 0.00 33408 0
sdj 104.85 12465.67 0.00 33408 0
sdk 3.73 5.97 10.45 16 28
sdl 4.10 11.94 5.97 32 16
sdm 5.22 14.93 7.46 40 20
md0 0.00 0.00 0.00 0 0
md2 8.58 26.87 7.46 72 20
srv:/home/brad# cat /proc/mdstat
Personalities : [raid0] [raid5] [raid6]
md2 : active raid5 sdl[0] sdm[2] sdk[1]
488396800 blocks level 5, 128k chunk, algorithm 2 [3/3] [UUU]
md0 : active raid5 sda1[0] sdj1[9] sdi1[8] sdh1[7] sdg1[6] sdf1[5] sde1[4] sdd1[3] sdc1[2] sdb1[1]
2206003968 blocks level 5, 128k chunk, algorithm 0 [10/10] [UUUUUUUUUU]
[===>.................] resync = 17.4% (42765824/245111552) finish=501.9min speed=6716K/sec
unused devices: <none>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: "Rebuild" speed on a forced resync
2005-01-11 9:47 "Rebuild" speed on a forced resync Brad Campbell
@ 2005-01-12 0:33 ` Neil Brown
2005-01-14 18:34 ` Brad Campbell
2005-01-12 0:48 ` Guy
1 sibling, 1 reply; 5+ messages in thread
From: Neil Brown @ 2005-01-12 0:33 UTC (permalink / raw)
To: Brad Campbell; +Cc: RAID Linux
On Tuesday January 11, brad@wasp.net.au wrote:
> G'day all,
>
> Just started my big raid using mdadm --update resync to ensure the parity blocks are A-OK after a
> kernel panic, and I have been monitoring my Disk IO with
> iostat -k 5
>
> Now this is an average for a 5 second period.
> I note I'm seeing about 12,456 Kilobytes/sec from each drive, but a cat /proc mdstat is giving me
> 6716 Kilobytes/sec. Given I'm doing a read consistency check I would expect an mdstat speed 9/10ths
> of my bulk per-drive read speed. (This array is sda -> sdj)
> Am I missing something really obvious?
>
> Kernel 2.6.10-bk10
>
> Regards,
> Brad
>
> avg-cpu: %user %nice %sys %iowait %idle
> 39.18 0.00 60.82 0.00 0.00
>
> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
> hda 0.00 0.00 0.00 0 0
> sda 97.76 12465.67 0.00 33408 0
> sdb 97.76 12465.67 0.00 33408 0
> sdc 97.76 12465.67 0.00 33408 0
So this is a 5 second sample...
In 5 seconds, 33408 kB were read.
That's 6681.6 kB/sec according to my calculator.
So it looks like iostat is reporting something wrongly. I would look
there first.
NeilBrown
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: "Rebuild" speed on a forced resync
2005-01-11 9:47 "Rebuild" speed on a forced resync Brad Campbell
2005-01-12 0:33 ` Neil Brown
@ 2005-01-12 0:48 ` Guy
2005-01-12 4:31 ` Brad Campbell
1 sibling, 1 reply; 5+ messages in thread
From: Guy @ 2005-01-12 0:48 UTC (permalink / raw)
To: 'Brad Campbell', 'RAID Linux'
On my system, iostat only reports since re-boot. Not since last run of
iostat. I use "sar -d" for current speeds. In the past, sar has agreed
with /dev/mdstat.
Note, with sar -d, sectors/s are 512 bytes.
Guy
-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Brad Campbell
Sent: Tuesday, January 11, 2005 4:48 AM
To: RAID Linux
Subject: "Rebuild" speed on a forced resync
G'day all,
Just started my big raid using mdadm --update resync to ensure the parity
blocks are A-OK after a
kernel panic, and I have been monitoring my Disk IO with
iostat -k 5
Now this is an average for a 5 second period.
I note I'm seeing about 12,456 Kilobytes/sec from each drive, but a cat
/proc mdstat is giving me
6716 Kilobytes/sec. Given I'm doing a read consistency check I would expect
an mdstat speed 9/10ths
of my bulk per-drive read speed. (This array is sda -> sdj)
Am I missing something really obvious?
Kernel 2.6.10-bk10
Regards,
Brad
avg-cpu: %user %nice %sys %iowait %idle
39.18 0.00 60.82 0.00 0.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hda 0.00 0.00 0.00 0 0
sda 97.76 12465.67 0.00 33408 0
sdb 97.76 12465.67 0.00 33408 0
sdc 97.76 12465.67 0.00 33408 0
sdd 97.76 12465.67 0.00 33408 0
sde 97.76 12465.67 0.00 33408 0
sdf 98.51 12465.67 0.00 33408 0
sdg 98.51 12465.67 0.00 33408 0
sdh 98.88 12465.67 0.00 33408 0
sdi 107.09 12465.67 0.00 33408 0
sdj 104.85 12465.67 0.00 33408 0
sdk 3.73 5.97 10.45 16 28
sdl 4.10 11.94 5.97 32 16
sdm 5.22 14.93 7.46 40 20
md0 0.00 0.00 0.00 0 0
md2 8.58 26.87 7.46 72 20
srv:/home/brad# cat /proc/mdstat
Personalities : [raid0] [raid5] [raid6]
md2 : active raid5 sdl[0] sdm[2] sdk[1]
488396800 blocks level 5, 128k chunk, algorithm 2 [3/3] [UUU]
md0 : active raid5 sda1[0] sdj1[9] sdi1[8] sdh1[7] sdg1[6] sdf1[5] sde1[4]
sdd1[3] sdc1[2] sdb1[1]
2206003968 blocks level 5, 128k chunk, algorithm 0 [10/10]
[UUUUUUUUUU]
[===>.................] resync = 17.4% (42765824/245111552)
finish=501.9min speed=6716K/sec
unused devices: <none>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: "Rebuild" speed on a forced resync
2005-01-12 0:48 ` Guy
@ 2005-01-12 4:31 ` Brad Campbell
0 siblings, 0 replies; 5+ messages in thread
From: Brad Campbell @ 2005-01-12 4:31 UTC (permalink / raw)
To: Guy; +Cc: 'RAID Linux'
Guy wrote:
> On my system, iostat only reports since re-boot. Not since last run of
> iostat. I use "sar -d" for current speeds. In the past, sar has agreed
> with /dev/mdstat.
>
run iostat 5 and it will report since last reboot on the first itteration, then from then on it only
reports since the last itteration and will update every 5 seconds. Same as vmstat does.
Regards,
Brad
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: "Rebuild" speed on a forced resync
2005-01-12 0:33 ` Neil Brown
@ 2005-01-14 18:34 ` Brad Campbell
0 siblings, 0 replies; 5+ messages in thread
From: Brad Campbell @ 2005-01-14 18:34 UTC (permalink / raw)
To: Neil Brown; +Cc: RAID Linux
Neil Brown wrote:
> On Tuesday January 11, brad@wasp.net.au wrote:
>
>>G'day all,
>>
>>Just started my big raid using mdadm --update resync to ensure the parity blocks are A-OK after a
>>kernel panic, and I have been monitoring my Disk IO with
>>iostat -k 5
>>
>>Now this is an average for a 5 second period.
>>I note I'm seeing about 12,456 Kilobytes/sec from each drive, but a cat /proc mdstat is giving me
>>6716 Kilobytes/sec. Given I'm doing a read consistency check I would expect an mdstat speed 9/10ths
>>of my bulk per-drive read speed. (This array is sda -> sdj)
>>Am I missing something really obvious?
>>
>>avg-cpu: %user %nice %sys %iowait %idle
>> 39.18 0.00 60.82 0.00 0.00
>>
>>Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
>>hda 0.00 0.00 0.00 0 0
>>sda 97.76 12465.67 0.00 33408 0
>>sdb 97.76 12465.67 0.00 33408 0
>>sdc 97.76 12465.67 0.00 33408 0
>
>
> So this is a 5 second sample...
> In 5 seconds, 33408 kB were read.
> That's 6681.6 kB/sec according to my calculator.
>
> So it looks like iostat is reporting something wrongly. I would look
> there first.
Ok, fair call on those stats. Having said that, we are talking 6.6 MB/sec per disk. Do I take it the
/proc/mdstat figure of 6 MB/sec is not a total array rebuild speed, but a speed per array member?
Regards,
Brad
^ permalink raw reply [flat|nested] 5+ messages in thread
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2005-01-11 9:47 "Rebuild" speed on a forced resync Brad Campbell
2005-01-12 0:33 ` Neil Brown
2005-01-14 18:34 ` Brad Campbell
2005-01-12 0:48 ` Guy
2005-01-12 4:31 ` Brad Campbell
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