On Mon, Mar 05, 2007 at 11:08:28AM -0500, Mark Hahn wrote: > writing to different sections of a file is probably wrong on any > networked FS, since there will inherently be obscure interactions > with the size and alignment of the writes vs client pagecache,
I'm rather surprised to see that sentiment on a mailing list for high performance clusters :> I would contend that writing to different sections of a file *must* be supported by any file system deployed on a cluster. How else would you get good performance from MPI-IO? PVFS, GPFS, and Lustre all suppoort simultaneous writes to different sections of a file. > in my experience, people who expect it to "just work" have an > incredibly naive model of how a network FS works (ie, write() > produces an RPC direct to the server) I agree that the POSIX API and consistency semantics make it difficult to achieve high I/O rates for common scientific workloads, and that NFS is probably not the best solution for those truly parallel workloads. Fortunately, there are good alternatives out there. ==rob -- Rob Latham Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF Argonne National Lab, IL USA B29D F333 664A 4280 315B _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
