I have been looking into htcp on some servers at the UK Tier1.
We did not see a major improvement in rates for completed transfers. We cannot say at the moment if the change has increased our percentage of successful transfers.
How did you observe this improvement?
How are you only applying changes to transfers for channels on a single FTS channel?
I would like more info ( off list) regarding the setup to see if particular disk server to diskserver transfers are faster between SASRA and RAL.
Thanks.
Brian
-----Original Message-----
From: LHC Computer Grid - Rollout [mailto:[log in to unmask]] On Behalf Of Lorne Levinson
Sent: 12 March 2012 21:29
To: [log in to unmask]
Subject: [LCG-ROLLOUT] bugs in TCP congestion algorithms
According to http://fasterdata.es.net/fasterdata/host-tuning/linux/ there are problems with the Linux TCP network congestion algorithms:
"NOTE: There seem to be bugs in both bic and cubic for a number of versions of the Linux kernel up to version 2.6.33. We recommend using htcp with older kernels to be safe."
The FTS channel from SARA to Weizmann has been changed to use htcp and indeed throughput has improved and timeouts have been reduced. (The SARA end is 10G but the Weizmann end is only 1G.) Do others have experience with tcp congestion algorithms?
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