Hi Derek,
Derek Feichtinger wrote:
> Hi,
>
> This is slightly off-topic, but nontheless important for the setup of large
> direct attached storage systems typically used with xrootd. Maybe some of you
> have good suggestions or experiences.
>
Well, I don't know exactly your requirements, but wouldn't it be
sufficient to look at the traffic by making an average of the data seen
by each client after the file close ?
Another (better) way could be to setup XrdMon. Why not ?
Fabrizio
> For our next upgrade of our Tier2 I would need a benchmark with which I can
> measure whether I can satisfy an I/O requirement per worker node (WN, or CPU
> core). This has to be tested while all WNs are reading in parallel from all
> file servers. I just want to assume that the clients from the WNs are reading
> in a nicely distributed fashion from the file servers, e.g. in the case of 10
> file servers and 150 WNs, I would assume that in average 15 WNs are reading
> at the same time from any file server. But any combination of 15 WNs must be
> able to yield the desired bandwidth.
>
> Naturally, this benchmark is targeted at mimicking a cluster running analysis
> applications.
>
> A primitive test (but not exactly matching the use case) could be using
> netperf or iperf in UDP mode. E.g. the file servers would receive packets
> from the required fraction of worker nodes (The sending intervals and packet
> sizes can be set for netperf). One would gradually increase the sending rate
> per worker node until UDP packet loss is observed.
>
> I'm glad for any suggestions.
>
> Cheers,
> Derek
>
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