Thanks both Barry and Andrew

I'd love to be able to provide some numbers but a lot of this is hedge betting whilst there's budget available, I'm sure an environment we're all used to.

I'll probably get 2*10Gb/s to the data centre for GPFS and all other traffic. I can perhaps convince our networks team to QoS this.

At present, there's no latency figures though we're looking at a 30 mile point to point distance over a managed service, I won't go into the minutiae of higher education networking in the UK, we're hoping for <5ms.

I expect a good mixture of read/write, I expect growth in IO will be higher on the local side than the DC.

The GPFS nodes are running RHEL 6.5 so 2.6.32.

It doesn't seem obvious to me how one should size the capacity of the local AFM cache as a proportion of the primary storage and whether it's self-purging. I expect that we'd be looking at ~ 1 PB at the DC within the lifetime of the existing hardware.

Thanks again for assistance, knowing that there are people out there doing this makes me feel that it's worth running up a demo.

Tom





On 04/07/2014 16:07, Barry Evans wrote:
Hi Tom,

Couple of quick ones:

Do you know what the latency and line distance is likely to be? What's
the rated bandwidth on the line? Is the workload at the 'local' site
fairly mixed in terms of reads/writes? What is the kernel version on the
current cluster?

Regards,
Barry


Tom King <mailto:[email protected]>
1 July 2014 17:39
Hi

I've recently adopted a small two node GPFS cluster which is likely to
be relocated to an off-site datacentre in the near future and I'm
concerned that latency times are going to be impacted for on-site users.

My reading of AFM is that an Independent Writer cache held on-site
could mitigate this and was wondering whether anybody had any
experience of using AFM caches in this manner.

Thanks

Tom King




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