Unstable speed or correct?

Unstable speed or correct?

[Pol Hallen]

Hi folks :-)

I've a raid6 sw (6disks from 1.5Tb) asus p5b-e.

Yestarday I done some checks tests and I see this:

http://fuckaround.org/nuvola/

is it correct (read) speed or is there a problem?

The read line oscillate and I don't understand if there a problem.

hdparm, smartctl and other diagnostic tool doesn't report any problem..

raid6 is correctly runs.

Any idea?

thanks!

Pol

Re: Unstable speed or correct?

[Pol Hallen]

> What benchmark program did you use for the test? Also, was there any other
> programs running at the same time? Was the machine in single-user (init 1)
> state?

hello :-)

dd if=/dev/zero of=/share/raid6/1Gb bs=1024 count=1000000
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB) copied, 12.1632 s, 84.2 MB/s

dd if=/dev/zero of=/share/raid6/10Gb bs=1024 count=10000000
10000000+0 records in
10000000+0 records out
10240000000 bytes (10 GB) copied, 142.021 s, 72.1 MB/s

That graphic with palimptest (gnome-disk-utility).

No other applications uses raid (I'm on init 2 but samba, ftp, and other 
daemons are off)

iostat not show me any activity by raid, so I think there is not programs that 
runs on array.

thanks :-) 

Pol

Unstable speed or correct?

[Durval Menezes]

Hello Pol.

On Thu, Jun 9, 2011 at 6:02 AM, Pol Hallen <raid2@fuckaround.org> wrote:
>
> > What benchmark program did you use for the test? Also, was there any other
> > programs running at the same time? Was the machine in single-user (init 1)
> > state?
>
> hello :-)
>
> dd if=/dev/zero of=/share/raid6/1Gb bs=1024 count=1000000
> 1000000+0 records in
> 1000000+0 records out
> 1024000000 bytes (1.0 GB) copied, 12.1632 s, 84.2 MB/s
>
> dd if=/dev/zero of=/share/raid6/10Gb bs=1024 count=10000000
> 10000000+0 records in
> 10000000+0 records out
> 10240000000 bytes (10 GB) copied, 142.021 s, 72.1 MB/s

The above dd's seem much more consistent than the graph.

> That graphic with palimptest (gnome-disk-utility).

I'm not familiar with this program (BTW, you mean "palimpsest",
right?), and I've run it for the first time on my system (M4A785-M
with Phenon-II X6 1055T, 4GB RAM, with 3 x ST31500541AS 1.5TB 3.5"
5900RPM HDs plugged directly onto the motherboard's SB700 SATA
controller, running Ubuntu Lucid Lynx 10.04.1 LTS, kernel
2.6.32-32-generic; the 3 HDs are mounted as a RAID5 md device and
dedicated to user data-only storage and mounted as /usr2, the root
filesystem runs on a separate SSD disk). Here's my palimpsest graph:
http://durval.com/felwithe_raid5_palimpsest_ro_20110609.jpg

Note that it shows much less "jitter" (local variation) than your graph.

> No other applications uses raid (I'm on init 2 but samba, ftp, and other
> daemons are off)
>
> iostat not show me any activity by raid, so I think there is not programs that
> runs on array.

This is very strange... concurrent access by other programs would
certainly explain the variation on your graph.

I would try running some other benchmark that can be run on
single-user state to see if the variation remains. If it does, then I
would conclude that there's something wrong (possibly on your
hardware, like a failing disk doing retries/reseeks).

Cheers,
--
  Durval Menezes.


>
> thanks :-)
>
> Pol
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Re: Unstable speed or correct?

[Pol Hallen]

> I'm not familiar with this program (BTW, you mean "palimpsest",
> right?)

yep :-)

> I would try running some other benchmark

iozone3 and bonnie?

Do u known other bench programs?

> that can be run on
> single-user

next day I'll try do these benchs to init 1

>if it does, then I
> would conclude that there's something wrong (possibly on your
> hardware, like a failing disk doing retries/reseeks).

I already examined all disks by smartclt, hdparm and seem there aren't 
problems :-/

Is ram a possible problem?

How hardware test I'll do?

thanks :-)

Pol

Re: Unstable speed or correct?

[Pol Hallen]

init 1 raid 6 performance:

http://fuckaround.org/nuvola/?p=17

iostat md0 -x 1:

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz 
avgqu-sz   await  svctm  %util
md0               0.00     0.00    0.00    0.00     0.00     0.00     0.00     
0.00    0.00   0.00   0.00

:-(((

Pol