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Storage on Rum & Kugel ?

 

 

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reg at elconas

Aug 28, 2008, 1:39 PM

Post #1 of 3 (237 views)
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Storage on Rum & Kugel ?

Hello,

I just watched the recording of the performance tuning webinar. The Q&A
points to
http://www.drbd.org/community/wiki/?tx_drwiki_pi1%5Bkeyword%5D=performance
for the specs of rum & kugel.

I wonder what storage subsystem on rum & kugel looks like ? (Controler +
HDD) ?

Thanks,
Robert
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lars.ellenberg at linbit

Sep 3, 2008, 12:45 AM

Post #2 of 3 (204 views)
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Re: Storage on Rum & Kugel ? [In reply to]

On Thu, Aug 28, 2008 at 10:39:30PM +0200, Robert Heinzmann (ml) wrote:
> Hello,
>
> I just watched the recording of the performance tuning webinar. The Q&A
> points to
> http://www.drbd.org/community/wiki/?tx_drwiki_pi1%5Bkeyword%5D=performance
> for the specs of rum & kugel.
>
> I wonder what storage subsystem on rum & kugel looks like ? (Controler +
> HDD) ?

ah, right.
that is an Adaptec 3405 RAID5 V1.0
with battery backup unit for the cache
with 4x FUJITSU MAX3073RC in RAID5
as PV of LVM2.
drbd and everything else is sitting in LVs on that.

btw, when you have a non-volatily,
battery backed up write cache in the controller,
don't forget to disable the (typically volatile!) on-disk cache.
or you may face data loss on power outage anyways.
you may enable the read cache on disk, if you think it is worth it.

in this setup, that was done by
modprobe sg
for i in `seq 4`; do sdparm -s WCE=0,RCD=0 -S /dev/sg$i ; done

see man sdparm for details,
and your controller manual for other ways to achieve the same
if the single disks are not visible as sg devices to the OS.

cheers,

--
: Lars Ellenberg
: LINBIT HA-Solutions GmbH
: DRBD®/HA support and consulting http://www.linbit.com

DRBD® and LINBIT® are registered trademarks
of LINBIT Information Technologies GmbH
__
please don't Cc me, but send to list -- I'm subscribed
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werner.fischer at fh-hagenberg

Sep 4, 2008, 2:11 AM

Post #3 of 3 (197 views)
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Re: Storage on Rum & Kugel ? [In reply to]

On Wed, 2008-09-03 at 09:45 +0200, Lars Ellenberg wrote:
> btw, when you have a non-volatily,
> battery backed up write cache in the controller,
> don't forget to disable the (typically volatile!) on-disk cache.
> or you may face data loss on power outage anyways.
> you may enable the read cache on disk, if you think it is worth it.
>
> in this setup, that was done by
> modprobe sg
> for i in `seq 4`; do sdparm -s WCE=0,RCD=0 -S /dev/sg$i ; done
>
> see man sdparm for details,
> and your controller manual for other ways to achieve the same
> if the single disks are not visible as sg devices to the OS.
I have done some tests with a very nice perl script from
http://brad.livejournal.com/2116715.html with different RAID controllers
(Adpatec, Areca, 3ware, and SATA-onboard) and documented the results (in
German) here:
http://www.thomas-krenn.com/de/wiki/Cache_Einstellungen_von_RAID_Controllern_und_Festplatten#Einstellungen_f.C3.BCr_sicheren_Betrieb

One of the controllers I've tested was an Adaptec 5405 - with this
controller you can use the arcconf CLI tool from Adaptec to disable the
cache of a disk, e.g. for the first disk:
arcconf SETCACHE 1 DEVICE 0 0 wt

PS: I've also done some consistency tests and provided some infos on
that, too:
http://www.thomas-krenn.com/de/wiki/Konsistenz_des_RAIDs_%C3%BCberpr%C3%BCfen

best regards,
Werner

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