Miles Nordin wrote:
"djm" == Darren J Moffat <darr...@opensolaris.org> writes:
djm> If you only present a single lun to ZFS it may not be able to
djm> repair any detected errors.
And also the problems with pools becoming corrupt and unimportable,
especially when the SAN reboots or loses connectivity and the host
does not, that people like to keep forgetting. :(
We forget because it is no longer a problem ;-)
>> And isn't that a waste of a high performing RAID array (EMC) ?
djm> That assumes it is actually faster - it might not be.
IIRC in general people have found RAID5/6 delivers higher iops than
raidz/raidz2 when both are in the same width.
Raidz will likely outperform RAID-5 on small, random writes.
RAID-5 will likely outperform raidz for small, random reads.
If you want your cake, and want to eat it, too, then you'll probably
not look to RAID-5 or raidz.
Also the EMC array will
be more robust in terms of a disk failing without taking down the host
than ZFS will be---in either case you'll not lose data, but ZFS is
likely to freeze for minutes or crash if a disk fails, and might take
longer to notice a disk which fails by becoming 100x slower (which is
not strange) than EMC.
I think it is disingenuous to compare an enterprise-class RAID
array with the random collection of hardware on which Solaris
runs. There is a damn good reason why an enterprise-class
array vendor can offer such high data availability and it is the
same reason why their products cost so much -- they can
tightly control and integrate the components.
And finally it's probably simpler to
administer as a single LUN though of course one can argue pointlessly
all day about what one thinks is clearly the best way to administer
things.
+1
-- richard
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
