0n Thu, Apr 30, 2009 at 11:11:55AM -0500, Bob Friesenhahn wrote:
>On Thu, 30 Apr 2009, Wilkinson, Alex wrote:
>>
>> I currently have a single 17TB MetaLUN that i am about to present to an
>> OpenSolaris initiator and it will obviously be ZFS. However, I am
constantly
>> reading that presenting a JBOD and using ZFS to manage the RAID is best
>> practice ? Im not really sure why ? And isn't that a waste of a high
performing
>> RAID array (EMC) ?
>
>The JBOD "advantage" is that then ZFS can schedule I/O for the disks
>and there is less chance of an unrecoverable pool since ZFS is assured
>to lay out redundant data on redundant hardware and ZFS uses more
>robust error detection than the firmware on any array. When using
>mirrors there is considerable advantage since writes and reads can be
>concurrent.
>
>That said, your EMC hardware likely offers much nicer interfaces for
>indicating and replacing bad disk drives. With the ZFS JBOD approach
>you have to back-track from what ZFS tells you (a Solaris device ID)
>and figure out which physical drive is not behaving correctly. EMC
>tech support may not be very helpful if ZFS says there is something
>wrong but the raid array says there is not. Sometimes there is value
>with taking advantage of what you paid for.
So forget ZFS and use UFS ? Or use UFS with a ZVOL ? Or Just use Vx{VM,FS} ?
It kinda sux that you get no benefit from using such a killer volume manager
+ filesystem with an EMC array :(
-aW
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