Phillip Fiedler wrote:
Thanks for the input. So, I'm trying to meld the two replies and come up with a
direction for my case and maybe a "rule of thumb" that I can use in the future
(i.e., near future until new features come out in zfs) when I have external storage
arrays that have built in RAID.
At the moment, I'm hearing that using h/w raid under my zfs may be better for some
workloads and the h/w hot spare would be nice to have across multiple raid groups, but
the checksum capabilities in zfs are basically nullified with single/multiple h/w lun's
resulting in "reduced protection." Therefore, it sounds like I should be
strongly leaning towards not using the hardware raid in external disk arrays and use them
like a JBOD.
The bit ...
the checksum capabilities in zfs are basically nullified with single/multiple h/w
lun's resulting in "reduced protection."
is not accurate. With one large LUN, then yes, you can only detect
errors. With multiple LUNs in a mirror or RAIDZ{2} then you can correct
errors.
The big reasons for continuing to use hw raid is speed, in some cases,
and heterogeneous environments where you can't farm out non-raid
protected LUNs and raid protected LUNs from the same storage array. In
some cases the array will require a raid protection setting, like the
99x0, before you can even start farming out storage.
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