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.
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
--
Dr. Derek Feichtinger Tel: +41 56 310 47 33
AIT Group email: [log in to unmask]
PSI http://people.web.psi.ch/feichtinger
CH-5232 Villigen PSI
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