[Lustre-discuss] Lustre performance differences between 1.6.4.3 and 1.6.5

[Hayes, Robert N]

We have been troubleshooting a major performance issue with out Lustre systems when switching from 1.6.4.3 to 1.6.5.
Using a patchless client and running a single thread, single file (50GB) dd copy, the 1.6.4.3 client wrote up to 1.3GB/s. Using the same system and changing only the client to 1.6.5, write speed went down to 700MB/s.
We found one configuration option different by default between the two clients. In 1.6.4.3, checksum is disabled by default. In 1.6.5, checksum is enabled by default. Disabling checksum on the 1.6.5 client resulted in a performance increase to 1.1GB/s.
Question - are there other option changes between 1.6.4.3 and 1.6.5 that might account for the remaining 200MB/s loss in performance?

Bob Hayes
System Administrator
Intel-SSG-DRD-DP
Office:  253-371-3040
Cell:     253-441-5482
e-mail: robert.n.hayes at Intel.Com<mailto:robert.n.hayes at Intel.Com>

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