> > A 6 disk raidz set is not optimal for random reads, since each disk in=20 > > the raidz set needs to be accessed to retrieve each item. > > I don't understand, if the file is contained within a single stripe, why > would it need to access the other disks, if the checksum of the stripe > is OK?
Because you have to read the entire stripe (which probably spans all the disks) to verify the checksum. With a traditional Raid5 setup, there is no checksum, so there is no need to read the entire stripe for a small read. It may need only a single disk to satisfy the read. > Also, why wouldn't it be able to concurrently access different > disks for multiple reads? In a random read situation, you'll likely have to read one slice (on all the disks), then seek and read a separate slice (on all the disks). That limits single-threaded random read throughput. -- Darren Dunham [EMAIL PROTECTED] Senior Technical Consultant TAOS http://www.taos.com/ Got some Dr Pepper? San Francisco, CA bay area < This line left intentionally blank to confuse you. > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
