On Thu, 20 Oct 2011, Fajar A. Nugraha wrote:
On Thu, Oct 20, 2011 at 7:56 AM, Dave Pooser <dave....@alfordmedia.com> wrote:
On 10/19/11 9:14 AM, "Albert Shih" <albert.s...@obspm.fr> wrote:
When we buy a MD1200 we need a RAID PERC H800 card on the server
No, you need a card that includes 2 external x4 SFF8088 SAS connectors.
I'd recommend an LSI SAS 9200-8e HBA flashed with the IT firmware-- then
it presents the individual disks and ZFS can handle redundancy and
recovery.
Exactly, thanks for suggesting an exact controller model that can
present disks as JBOD.
With hardware RAID, you'd pretty much rely on the controller to behave
nicely, which is why I suggested to simply create one big volume for zfs
to use (so you pretty much only use features like snapshot, clones, etc,
but don't use zfs self healing feature). Again, others might (and have)
disagree and suggest using volumes for individual disk (even when you're
still relying on hardware RAID controller). But ultimately there's no
question that the best possible setup would be to present the disks as
JBOD and let zfs handle it directly.
I saw something interesting and different today, which I'll just throw
out.
A buddy has a HP370 loaded with disks (not the only machine that provides
these services, rather the one he was showing off). The 370's disks are
managed by the underlying hardware RAID controller, which he built as
multiple RAID1 volumes.
ESXi 5.0 is loaded and in control of the volumes, some of which are
partitioned. Consequently, his result is vendor supported interfaces
between disks, RAID controller, ESXi, and managing/reporting software.
The HP370 has multiple FreeNAS instances whose "disks" are the "disks"
(volumes/partitions) from ESXi (all on the same physical hardware). The
FreeNAS instances are partitioned according to their physical and logical
function within the infrastructure, whether by physical or logical
connections. The FreeNAS instances then serves its "disks" to consumers.
We have not done any performance testing. Generally, his NAS consumers are
not I/O pigs though we want the best performance possible (some consumers
are over the WAN resulting in any HP/ESXi/FreeNAS performance issues
possibly moot). (I want to do some performance testing because, well, it
may have significant amusement value.) A question we have is whether ZFS
(ARC, maybe L2ARC) within FreeNAS is possible or would provide any value.
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