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.
--
Robert Milkowski
http://milek.blogspot.com
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