On Jun 24, 2010, at 10:42 AM, Robert Milkowski <mi...@task.gda.pl> wrote:
> On 24/06/2010 14:32, Ross Walker wrote: >> On Jun 24, 2010, at 5:40 AM, Robert Milkowski<mi...@task.gda.pl> wrote: >> >> >>> On 23/06/2010 18:50, Adam Leventhal wrote: >>> >>>>> Does it mean that for dataset used for databases and similar environments >>>>> where basically all blocks have fixed size and there is no other data all >>>>> parity information will end-up on one (z1) or two (z2) specific disks? >>>>> >>>>> >>>> No. There are always smaller writes to metadata that will distribute >>>> parity. What is the total width of your raidz1 stripe? >>>> >>>> >>>> >>> 4x disks, 16KB recordsize, 128GB file, random read with 16KB block. >>> >> From what I gather each 16KB record (plus parity) is spread across the raidz >> disks. This causes the total random IOPS (write AND read) of the raidz to be >> that of the slowest disk in the raidz. >> >> Raidz is definitely made for sequential IO patterns not random. To get good >> random IO with raidz you need a zpool with X raidz vdevs where X = desired >> IOPS/IOPS of single drive. >> > > I know that and it wasn't mine question. Sorry, for the OP... _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss