On Feb 23, 2010, at 9:16 AM, Felix Buenemann wrote: > Hi, > > as it turns out to be pretty difficult (or expensive), to find high > performance dedicated ZIL devices, I had another thought: > > If using a RAID controller with a large cache, eg. 4GB and battery backup in > JBOD mode and using on disk ZIL – wouldn't the controller cache work as a > great ZIL accelerator, requiring no dedicated ZIL?
Yes. ZIL is a performance problem for HDD JBODs, not so much on devices with fast, nonvolatile write caches. > If my understanding is correct, a battery backed RAID controller will ignore > cache flush commands and thus the controller cache would be a very low > latency intermediate cache wich is preserved over power failure. Cache flush latency is orthogonal to slog latency. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance http://nexenta-atlanta.eventbrite.com (March 16-18, 2010) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
