On Wed, 9 Jun 2010, Edward Ned Harvey wrote:
disks. That is, specifically: o If you do a large sequential read, with 3 mirrors (6 disks) then you get 6x performance of a single disk.
Should say "up to 6x". Which disk in the pair will be read from is random so you are unlikely to get the full 6x.
o If you do a large sequential read, with 7-disk raidz (capacity of 6 disks) then you get 6x performance of a single disk.
Probably should say "up to 6x" as well. This configuration is more sensitive to latency and available disk IOPS becomes more critical.
o If you do a large sequential write, with 3 mirrors (6 disks) then you get 3x performance of a single disk.
Also an "up to" type value. Perhaps you will only get 1.5X because of some I/O bottleneck between the CPU and the mirrored disks (i.e. two writes at once may cause I/O contention).
These rules of thumb are not terribly accurate. If performance is important, then there is no substitute for actual testing.
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
