Hi Sebastian,
Am 15.01.2014 13:55, schrieb Sebastien Han:
Hi Alexandre,
Are you going with a 10Gb network? It’s not an issue for IOPS but more for the bandwidth. If so read the following:
I personally won’t go with a ratio of 1:6 for the journal. I guess 1:5 (or even 1:4) is preferable.
SAS 10K gives you around 140MB/sec for sequential writes.
So if you use a journal with an SSD, you expect at least 140MB if you don’t want to slow things down.
If you do so 140*10 (disks): fulfil your 10GB bandwidth already. So either you don’t need that much disks either you don’t need SSDs.
It depends on the performance that you want to achieve.
Another thing, I also won’t use the DC S3700 since this disk was definitely made for IOPS intensive applications. The journal is purely sequential (small seq block, IIRC Stephan mentioned 370k blocks).
I will instead use with a SSD with large sequential capabilities like 525 series 120GB.
Two important things. Your external controller or onboard port should be
SATA III otherwise i've seen degraded sequential SSD speed.
THe DC S3700 isn't good as squential but the 520 or 525 series has the
problem that it doesn't have a capicator. We've used Intel SSDs since
the 160 series but for ceph we now go for Crucial m500 (has capicitor).
Greets,
Stefan
Cheers.
––––
Sébastien Han
Cloud Engineer
"Always give 100%. Unless you're giving blood.”
Phone: +33 (0)1 49 70 99 72
Mail: sebastien.han@xxxxxxxxxxxx
Address : 10, rue de la Victoire - 75009 Paris
Web : www.enovance.com - Twitter : @enovance
On 15 Jan 2014, at 12:47, Alexandre DERUMIER <aderumier@xxxxxxxxx> wrote:
Hello List,
I'm going to build a build a rbd cluster this year, with 5 nodes
I would like to have this kind of configuration for each node:
- 2U
- 2,5inch drives
os : 2 disk sas drive
journal : 2 x ssd intel dc s3700 100GB
osd : 10 or 12 x sas Seagate Savvio 10K.6 900GB
I see on the mailing that intank use dell r515.
I currently own a lot of dell servers and I have good prices.
But I have also see on the mailing that dell perc H700 can have some performance problem,
and also it's not easy to flash the firmware for jbod mode.
http://www.spinics.net/lists/ceph-devel/msg16661.html
I don't known if theses performance problem has finally been solved ?
Another option could be to use supermicro server,
they have some 2U - 16 disks chassis + one or two lsi jbod controller.
But, I have had in past really bad experience with supermicro motherboard.
(Mainly firmware bug, ipmi card bug,.....)
Does someone have experience with supermicro, and give me advise for a good motherboard model?
Best Regards,
Alexandre Derumier
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