On 03/10/12 09:29, Sriram Narayanan wrote:
At work, I have an R510, and R610 and an R710 - all with the H700 PERC
Based on experiments, it seems like there is no way to bypass the PERC
controller - it seems like one can only access the individual disks if
they are set up in RAID0 each.
This brings me to ask some questions:
a. Is it fine (in terms of an intelligent controller coming in the way
of ZFS) to have the PERC controllers present each drive as RAID0
b. Would there be any errors in terms of PERC doing things that ZFS is
not aware of and this causing any issues later ?
I had to produce a ZFS hybrid storage pool performance demo, and was
initially given a system with a RAID-only controller (different from
yours, but same idea).
I created the demo with it, but disabled the RAID's cache as that wasn't
what I wanted in the picture. Meanwhile, I ordered the non-RAID version
of the card.
When it came and I swapped it in. A couple of issues...
ZFS doesn't recognise any of the disks obviously, because they have
propitiatory RAID headers on them, so they have to be created again from
scratch. (That was no big deal in this case, and if it had been, I could
have done a zfs send and receive to somewhere else temporarily.)
The performance went up, a tiny bit for the spinning disks, and by 50%
for the SSDs, so the RAID controller was seriously limiting the IOPs of
the SSDs in particular. This was when SSDs were relatively new, and the
controllers may not have been designed with SSDs in mind. That's likely
to be somewhat different nowadays, but I don't have any data to show
that either way.
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