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Re: MySQL + NAS(NFS) - Possible solution?
Posted by: Darren Schreiber
Date: March 07, 2006 09:21AM

We are having a very similar problem - I see this thread is old, but hopefully not dead.

We have a very large InnoDB table (several million rows) that unfortunately can not be split. We assumed putting this on a SAN hosted environment would improve performance. When we tried it, we got very, very poor results. We have been looking at all the same things mentioned in this document alerady.

We used both dd and sysbench tool to benchmark performance of this server and found it to be very fast (150MB/sec) EXCEPT when fsyncs() were involved. If an fsync() was done after every 10 writes to disk, the performance dropped to 18MB/sec. I am not sure whether this is an indication of a kernel issue or a driver issue for the QLogic driver in use for connecting the SAN to the machine. Or whether this is a behavior of fsync itself that is expected due to the overhead in confirming a write to disk has succeeded and flushing associated buffers.

I also am unclear as to how often MySQL calls fsync().

Any light on this?

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Re: MySQL + NAS(NFS) - Possible solution?
March 07, 2006 09:21AM

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