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.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
