On Fri, Nov 21, 2008 at 14:35, Charles Menser <[EMAIL PROTECTED]> wrote:
> I have a 5 drive raidz2 pool which I have a iscsi share on. While
> backing up a MacOS drive to it I noticed some very strange access
> patterns, and wanted to know if what I am seeing is normal, or not.
>
> There are times when all five drives are accessed equally, and there
> are times when only three of them are seeing any load.
What does "zpool status" say? How are the drives connected? To what
controller(s)?
This could just be some degree of asynchronicity showing up. Take a
look at these two:
capacity operations bandwidth
pool used avail read write read write
---------- ----- ----- ----- ----- ----- -----
main_pool 852G 3.70T 361 1.30K 2.78M 10.1M
raidz2 852G 3.70T 361 1.30K 2.78M 10.1M
c5t5d0 - - 180 502 1.25M 3.57M
c5t3d0 - - 205 330 1.30M 2.73M
c5t4d0 - - 239 489 1.43M 2.81M
c5t2d0 - - 205 17 1.25M 26.1K
c5t1d0 - - 248 13 1.41M 25.1K
---------- ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
---------- ----- ----- ----- ----- ----- -----
main_pool 852G 3.70T 10 2.02K 77.7K 15.8M
raidz2 852G 3.70T 10 2.02K 77.7K 15.8M
c5t5d0 - - 2 921 109K 6.52M
c5t3d0 - - 9 691 108K 5.63M
c5t4d0 - - 9 962 105K 5.97M
c5t2d0 - - 9 1.30K 167K 8.50M
c5t1d0 - - 2 1.23K 150K 8.54M
---------- ----- ----- ----- ----- ----- -----
For c5t5d0, a total of 3.57+6.52 MB of IO happen: 10.09 MB;
For c5t3d0, a total of 2.73+5.63 MB of IO happen: 8.36 MB;
For c5t4d0, a total of 2.81+5.97 MB of IO happen: 8.78 MB;
For c5t2d0, a total of (~0)+8.50 MB of IO happen: 8.50 MB;
and for c5t1d0, a total of (~0) + 8.54 MB of IO happen: 8.54 MB.
So over time, the amount written to each drive is approximately the
same. This being the case, I don't think I'd worry about it too
much... but a scrub is a fairly cheap way to get peace of mind.
Will
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