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Thoughts on this spec:

Hi guys,

I would like some input on this spec to create a cluster:

3x HP DL380 G5 - Dual CPU (Xeon X5450) / 16GB memory

Each of the machines with come with 8x 146GB SAS drives but won't cut it for my needs. I am looking at replacing with Western Digital Red 1TB (WD10JFCX).

It will be for an ESXi enviroment so any thoughts, recommendations and advice is recommended before I pull the trigger.

TIA

Hi,

Generally it would be better if you can bump RAM to 32G since the node is used for both Ceph storage as well as iSCSI gateway.

Configure your RAID as RAID0, if you have battery backed write back use that.

Good luck.

Thanks for the reply.

What would the performance implications be if I only run 16GB to start?
Thanks again.

It varies a lot based on your hardware with your workload. I would suggest testing 2 configurations, one with single disk  RAID0  (or JBOD if your controller supports it but i doubt), the other with 2 disk RAID0 so we essentially half the number of OSDs which will require less resources. Ceph gives better performance with more OSDs but you should allocate 2G per OSD.

Perform your tests by simulating your max workload load  then  force shutdown one storage node during the test after writing at least 100G of data, this will put the highest stress on the system.  If you find the first configuration handle this well then use it else choose the second.

Technically we have performance tools: atop/collectl/sar bundled in PetaSAN you can use to monitor cpu/ram/disk load. If your %busy disk is loaded more than cpu/ram then configuration 1 is better else 2 is better. Good luck.