On Tue, Mar 10, 2009 at 05:57:16PM -0500, Bob Friesenhahn wrote: > On Tue, 10 Mar 2009, Moore, Joe wrote: > > >As far as workload, any time you use RAIDZ[2], ZFS must read the > >entire stripe (across all of the disks) in order to verify the > >checksum for that data block. This means that a 128k read (the > >default zfs blocksize) requires a 32kb read from each of 6 disks, > >which may include a relatively slow seek to the relevant part of the > >spinning rust. So for random I/O, even though the data is striped > > This is not quite true. Raidz2 is not the same as RAID6. ZFS has an > independent checksum for its data blocks. The traditional RAID type > technology is used to repair in case data corruption is detected.
What part isn't true? ZFS has a independent checksum for the data block. But if the data block is spread over multiple disks, then each of the disks have to be read to verify the checksum. -- Darren _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
