On Fri, 26 Jun 2009, NightBird wrote:
Thanks Ian. I read the best practices and undestand the IO limitation I have created for this vdev. My system is a built for maximize capacity using large stripes, not performance. All the tools I have used show no IO problems. I think the problem is memory but I am unsure on how to troubleshoot it.
Perhaps someone else has answered your question. The problem is not a shortage of I/O. The problem is that raidz and raidz2 do synchronized reads and writes (in a stripe) and so all of the disks in the stripe need to respond before the read or write can return. If one disk is a bit slower than the rest, then everything will be slower. With so many disks, the deck is stacked against you. Raidz can not use an infinite stripe size so the number of disks used for any given I/O is not all of the disks in the vdev, which may make finding the slow disk a bit more difficult.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
