On 11/27/2013 05:35 AM, Johannes Klarenbeek wrote:
Dear Ceph-users,
I was wondering if I could use a raspberry PI exclusively for ceph mons
only. Well, it doesn’t have to be a raspberry pi of course, but some
cheap, no fan, Athlon like server with 100Mps Ethernet connection in a
10 node 4Gb NIC per server ceph cluster. Just a thought.
What are the requirements for a ceph-mon only node anyway? Can I run
them without harddisks (PXE boot and a lot of ram for example)? And what
happens if I would add 2 monitors in my cluster, that totals up to 3?
Does a ceph-mon node need a second NIC team for cluster traffic only as
well?
I hope there are some guide lines on this. Thanks in advance!
Hi,
The lowest specced machines we've done relatively extensive mon
performance testing on were 4-core ARM9 nodes with 4GB of RAM back for
the cuttlefish release. After a number of fixes and optimizations we
could comfortably support around 200 OSDs with 3 ARM mons. That was
only with a limited number of clients though so your mileage may vary.
A pi would be tough as it's a lot slower and has far less memory.
Having a local SSD or HD is probably a good idea for leveldb. Multiple
network links are a nice to have, but not strictly necessary in this
price class.
If you are willing to spend a little more, there are other options.
Some of the thumbstick PCs have dualcore ARM9 CPUs, 2GB of RAM, and can
run Ubuntu for about $60-70. That might be good enough as mon nodes for
smallish clusters (especially if they are clocked at 2GHz+).
If you are willing to pay a little more, this is the board that I just
picked up for cheap Ceph testing:
http://www.amazon.com/ECS-Elitegroup-Motherboard-NM70-I2-1-0/dp/B00G237CYQ/ref=sr_1_1?ie=UTF8&qid=1385561872&sr=8-1&keywords=ecs+1037u
For ~$67 you get a mini-itx motherboard with a soldered on 17W dual core
1.8GHz ivy-bridge based Celeron (supports SSE4.2 CRC32 instructions!).
It has 2 standard dimm slots so no compromising on memory, on-board
gigabit eithernet, 3 3Gb/s + 1 6Gb/s SATA, and a single PCIE slot for an
additional NIC. This has the potential to make a very competent low
cost, lowish power OSD or mon server. The biggest downside is that it
doesn't appear to support ECC memory. Some of the newer Atoms appear
to, so that might be an option as well.
Good luck!
Regards,
Johannes
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