On Apr 17, 2010, at 11:51 AM, Edward Ned Harvey wrote: >> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> boun...@opensolaris.org] On Behalf Of Dave Vrona >> >> 1) Mirroring. Leaving cost out of it, should ZIL and/or L2ARC SSDs be >> mirrored ? > > IMHO, the best answer to this question is the one from the ZFS Best > Practices guide. (I wrote part of it.) > In short: > > You have no need to mirror your L2ARC cache device, and it's impossible even > if you want to for some bizarre reason. > > For zpool < 19, which includes all present releases of Solaris 10 and > Opensolaris 2009.06, it is critical to mirror your ZIL log device. A failed > unmirrored log device would be the permanent death of the pool.
I do not believe this is a true statement. In large part it will depend on the nature of the failure -- all failures are not created equal. It has also been shown that such pools are recoverable, albeit with tedious, manual procedures required. Rather than saying this is a "critical" issue, I could say it is "preferred." Indeed, there are *many* SPOFs in the typical system (any x86 system) which can be considered similarly "critical." Finally, you have choices -- you can use an HBA with nonvolatile write cache and avoid the need for separate log device. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
