On 08/27/2012 08:05 PM, Stephen Perkins wrote:
Given that "massive" is a relative term, I am as well... but I'm
also trying to reduce the footprint (power and space) of that
"massive" cluster.
I also
want to start small (1/2 rack) and scale as needed.
If you do end up testing Brazos processes, please post your results!
I think it really depends on what kind of performance you are aiming for.
Our stock 2U test boxes have 6-core opterons, and our SC847a has dual
6-core low power Xeon E5s. At 10GbE+ these are probably going to be
pushed pretty hard, especially during recovery.
I'm aiming for a Ceph cluster of a couple of hundred TB consisting out
of 5 or 6 racks full of 1U machines with each 4x 1TB.
Thinking along the lines of the approach of many 1U by 4 drive host (as
above) with no hardware RAID... what are the thoughts between SATAII (3G/s)
vs SATAIII (6G/s) and on 1G Ethernet versus 10G Ethernet.
While SATA3 offers more bandwidth you won't benefit that much with
7200RPM disks.
Buffer writes might go a bit faster, but it won't be shocking.
You will however notice the difference when using a SSD for journaling,
since the new SSDs are able to utilize the SATA3 bandwidth much better.
I think that 10G would be overkill for a node with just 4 OSDs running
on 4 disks in total, but you might want to look at trunking 2 1Gb NIC's
with LACP?
- Steve
P.S. I will be assuming a replication level of 3 copies and would probably
be looking at 10 nodes or less initially. Maybe populating with 6 drives
instead of 4 (if I can find the right chassis).
I'd go with 3 as well. Going with 2 would cause you to limp whenever
just one machine/disk fails.
If you want to go for 6 drives in 1U you'd be looking at 2.5" drives.
It's a bummer they are still so expensive when looking at price per GB.
Wido
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