> -----Original Message----- > From: Peter Grandi [mailto:[email protected]] > Sent: Thursday, June 02, 2011 4:10 PM > To: Roger Spellman > Cc: [email protected] > Subject: Re: [Lustre-discuss] Reads Starved > > Unfortunately these numbers are meaningless without an idea of > the storage system and the access patterns.
The storage system is a Dell MD3200. > > > But, when I have 10 clients doing reads, and a different 10 > > clients doing writes, the write performance barely drops, but > > the read performance drops to about 150 MB/s. > > This may be entirely the right thing for it to happen. Each test is doing large block, streaming I/O. The reads and write are accessing different files. I am running 1 thread per client. If I increase the thread count on the reads, the performance does increase, but not nearly to the level of the writes. I had increased max_rpcs quite large, as this gives excellent performance. However, this turns out to be the cause of this read/write disparity. The system can queue up many writes, but reads are issued one at a time. By decreasing max_rpcs, the read performance increased considerably. Roger Spellman Staff Engineer Terascala, Inc. 508-588-1501 www.terascala.com <http://www.terascala.com/> _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
