On 05/07/2013 03:36 PM, Barry O'Rourke wrote:
Hi,
With so few disks and the inability to do 10GbE, you may want to
consider doing something like 5-6 R410s or R415s and just using the
on-board controller with a couple of SATA disks and 1 SSD for the
journal. That should give you better aggregate performance since in
your case you can't use 10GbE. It will also spread your OSDs across
more hosts for better redundancy and may not cost that much more per GB
since you won't need to use the H700 card if you are using an SSD for
journals. It's not as dense as R515s or R720XDs can be when fully
loaded, but for small clusters with few disks I think it's a good
trade-off to get the added redundancy and avoid expander/controller
complications.
I hadn't considered lowering the specification and increasing the number
of hosts, that seems like a really viable option and not too much more
expensive. When you say the on-board controller do you mean the onboard
SATA or the H310 controller?
Good question on the controller. I suspect the on-board will be good
enough for 1GbE or even bonded 1GbE throughput levels. I've also heard
some mixed things about the H310 but haven't gotten to test one myself.
What I've seen in the past is that if you are only using spinning
disks, a controller with on-board cache will help performance quite a
bit. If you have an SSD drive for journals, you can get away with much
cheaper sata/SAS controllers. You mentioned earlier that the Dell SSDs
were quite expensive. Have you considered something like an Intel DC
S3700? If you can't get one through Dell, you might consider just doing
3 disks from Dell and adding one yourself (you could put OS and journals
on it, and use the 3 spinning disks for OSDs). This does have the
effect though of making the SSD a single point of failure (which is why
it's good to use the enterprise grade drive here I think).
Mark
Thanks,
Barry
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