On Thu, Aug 18, 2011 at 5:42 AM, NeilBrown <neilb@xxxxxxx> wrote:
> On Thu, 18 Aug 2011 02:26:17 +0200 Harald Nikolisin <hochglanz@xxxxxxxxx>
> wrote:
>
>> hi,
>>
>> I didn't want to complain in general about SW RAID-1 performance. I
>> simply think something is wrong with my setup and I have currently no
>> idea how to improve.
>>
>> The basic questions (where I did not find an answer, neither in FAQ's
>> nor in forum discussions) are.
>> a) Is it normal that the hard drives show an permanent utilization
>> (around 20%) without any noticeable actions on the computer?
>
> No. If the array is resyncing or recovering then you would expect
> utilization for as many hours as it takes - but that would show
> in /proc/mdstat.
>
>> b) Should (as long as no resync happens) the state of mdadm active or clean?
>
> If anything has been written to the device in the last 200msec (including
> e.g. access time updates) then expect it to be 'active'.
> If nothing has been written for 200msecc or more, then expect it to be clean.
>
> If you crash while it is active, a resync is needed.
> If you crash while it is clean, no resync is needed.
> If you don't crash at all .... that is best :-)
I think this info should be wikified if not yet.
btw, I've experimented a bit on my /boot array (it doesn't being
updated, checked with iostat ), and:
root@m2:~# for i in {1..5};do mdname="md0"; echo "iteration $i";
(mdadm --detail /dev/$mdname|grep 'State ';cat
/sys/block/$mdname/md/array_state;grep "$mdname :" /proc/mdstat);sleep
1;done
iteration 1
State : clean
clean
md0 : active raid1 sda1[0] sdb1[1]
iteration 2
State : clean
clean
md0 : active raid1 sda1[0] sdb1[1]
iteration 3
State : clean
clean
md0 : active raid1 sda1[0] sdb1[1]
iteration 4
State : clean
clean
md0 : active raid1 sda1[0] sdb1[1]
iteration 5
State : clean
clean
md0 : active raid1 sda1[0] sdb1[1]
so, mdadm --detail & array_state shows array is "clean", while
/proc/mdstat shows array is "active" (no reads/writes happen).
Some value is lieing or being misunderdstanded by me...
>
>
>
>>
>> cheers,
>> harald
>>
>> well, I have only 2 hard drives and no space for more..
>>
>> Am 16.08.2011 03:29, schrieb Roberto Spadim:
>> > try raid10 far layout
>> >
>> > 2011/8/15 Harald Nikolisin <hochglanz@xxxxxxxxx
>> > <mailto:hochglanz@xxxxxxxxx>>
>> >
>> > Since a long time I'm unhappy with the performance of my RAID-1 system.
>> > Investigation with atop and iostat unveils that the disk utilization is
>> > always on a certain level although nothing happens on the system. In the
>> > case of reading or writing files the utilization boosts always to 100%
>> > for a long time. Very ugly examples are "Firefox starting" or "zypper
>> > updates".
>> > That is snapshot of the output of iostat:
>> >
>> >
>> > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
>> > avgrq-sz avgqu-sz await svctm %util
>> > sda 0,00 0,00 0,00 7,33 0,00 43,33
>> > 5,91 0,33 43,18 33,32 24,43
>> > sdb 0,00 0,00 0,00 7,33 0,00 43,33
>> > 5,91 0,35 45,59 39,73 29,13
>> > md0 0,00 0,00 0,00 0,67 0,00 5,33
>> > 8,00 0,00 0,00 0,00 0,00
>> > md1 0,00 0,00 0,00 0,33 0,00 5,33
>> > 16,00 0,00 0,00 0,00 0,00
>> > md2 0,00 0,00 0,00 0,33 0,00 1,00
>> > 3,00 0,00 0,00 0,00 0,00
>> > md3 0,00 0,00 0,00 0,00 0,00 0,00
>> > 0,00 0,00 0,00 0,00 0,00
>> > md4 0,00 0,00 0,00 0,00 0,00 0,00
>> > 0,00 0,00 0,00 0,00 0,00
>> > md5 0,00 0,00 0,00 0,33 0,00 0,67
>> > 2,00 0,00 0,00 0,00 0,00
>> >
>> > I checked with mdadm if a resync happens or so, but this is not the
>> > case. The state says "active" on all RAID devices - btw. what is the
>> > difference to "clean" ?
>> >
>> > thanks for any hints,
>> > harald
>> > --
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>> >
>> >
>> >
>> >
>> > --
>> > Roberto Spadim
>> > Spadim Technology / SPAEmpresarial
>>
>>
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>
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--
Best regards,
[COOLCOLD-RIPN]
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