> If I'm not mistaken, a 3-way mirror is not
> implemented behind the scenes in
> the same way as a 3-disk raidz3. You should use a
> 3-way mirror instead of a
> 3-disk raidz3.
RAIDZ2 requires at least 4 drives, and RAIDZ3 requires at least 5 drives. But,
yes, a 3-way mirror is implemented tota
here are no writes in the queue).
Perhaps you are saying that they act like stripes for bandwidth purposes, but
not for read ops/sec?
-Rob
-Original Message-
From: Bob Friesenhahn [mailto:bfrie...@simple.dallas.tx.us]
Sent: Saturday, August 06, 2011 11:41 AM
To: Rob Cohen
Cc: zfs-dis
> I may have RAIDZ reading wrong here. Perhaps someone
> could clarify.
>
> For a read-only workload, does each RAIDZ drive act
> like a stripe, similar to RAID5/6? Do they have
> independant queues?
>
> It would seem that there is no escaping
> read/modify/write operations for sub-block writes
RAIDZ has to rebuild data by reading all drives in the group, and
reconstructing from parity. Mirrors simply copy a drive.
Compare 3tb mirros vs. 9x3tb RAIDZ2.
Mirrors:
Read 3tb
Write 3tb
RAIDZ2:
Read 24tb
Reconstruct data on CPU
Write 3tb
In this case, RAIDZ is at least 8x slower to resilver
I may have RAIDZ reading wrong here. Perhaps someone could clarify.
For a read-only workload, does each RAIDZ drive act like a stripe, similar to
RAID5/6? Do they have independant queues?
It would seem that there is no escaping read/modify/write operations for
sub-block writes, forcing the RA
Generally, mirrors resilver MUCH faster than RAIDZ, and you only lose
redundancy on that stripe, so combined, you're much closer to RAIDZ2 odds than
you might think, especially with hot spare(s), which I'd reccommend.
When you're talking about IOPS, each stripe can support 1 simultanious user.
Try mirrors. You will get much better multi-user performance, and you can
easily split the mirrors across enclosures.
If your priority is performance over capacity, you could experiment with n-way
mirros, since more mirrors will load balance reads better than more stripes.
--
This message post
As a follow-up, I tried a SuperMicro enclosure (SC847E26-RJBOD1). I have 3
sets of 15 drives. I got the same results when I loaded the second set of
drives (15 to 30).
Then, I tried changing the LSI 9200's BIOS setting for max INT 13 drives from
24 (the default) to 15. From then on, the Supe
Markus,
I'm pretty sure that I have the MD1000 plugged in properly, especially since
the same connection works on the 9280 and Perc 6/e. It's not in split mode.
Thanks for the suggestion, though.
--
This message posted from opensolaris.org
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zfs-dis
I have 15x SAS drives in a Dell MD1000 enclosure, attached to an LSI 9200-16e.
This has been working well. The system is boothing off of internal drives, on
a Dell SAS 6ir.
I just tried to add a second storage enclosure, with 15 more SAS drives, and I
got a lockup during Loading Kernel. I go
When running real data, as opposed to benchmarks, I notice that my l2arc stops
filling, even though the majority of my reads are still going to primary
storage. I'm using 5 SSDs for L2ARC, so I'd expect to get good throughput,
even with sequential reads.
I'd like to experiment with disabling t
Thanks, Richard. Your answers were very helpful.
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I have read some conflicting things regarding the ZFs record size setting.
Could you guys verify/correct my these statements:
(These reflect my understanding, not necessarily the facts!)
1) The ZFS record size in a zvol is the unit that dedup happens at. So, for a
volume that is shared to an
Thanks, Ian.
If I understand correctly, the performance would then drop to the same level as
if I set them up as separate volumes in the first place.
So, I get double the performance for 75% of my data, and equal performance for
25% of my data, and my L2ARC will adapt to my working set across b
I have a couple drive enclosures:
15x 450gb 15krpm SAS
15x 600gb 15krpm SAS
I'd like to set them up like RAID10. Previously, I was using two hardware
RAID10 volumes, with the 15th drive as a hot spare, in each enclosure.
Using ZFS, it could be nice to make them a single volume, so that I could
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