In the last episode (Jun 26), Joshua Isom said: > On 6/25/2011 9:32 PM, Damien Fleuriot wrote: > > On 25 Jun 2011, at 19:17, Joshua Isom<jri...@gmail.com> wrote: > >> I was wondering if anyone had tried using a decent USB flash drive for > >> the ZIL. I know it'd be hard finding one fast enough, but some from > >> patriot seem like they might be suitable for home use. Part of the > >> idea is to just minimize hard drive thrashing and the wear and tear > >> associated with it. If it helps prevent the drives from going bad, and > >> doesn't hurt performance too bad all the better. But if it's going to > >> hurt performance too much or not help prevent thrashing there isn't a > >> point. > > > > I stopped reading at the title. > > The answer is no. > > > > Grab a SSD for $80-120ish. > > Perhaps it would have helped to read the email. Part of the concern is > making sure the drives don't fail and not just throughput. > > Given that Kingston sells an SATA SSD for $40 that only gets writes at > 30mb/s write, and some USB drives might get up to 20mb/s. If I get two > drives and put them on different controllers, mirrored, I might get > acceptable performance. I may still loose performance, but if my drives > last a year longer, I can probably accept it. I'm ok with loosing some > performance, but I just don't want it dragging down the system. And if it > won't help the drives last longer there's no point.
A seaparate ZIL isn't meant to extend the lifetime of the hard drives; it's meant to accelerate the speed of sync writes. Those are pretty infrequent themselves, unless you're an NFS server. You'll see a couple syncs per commit on a database server, but compared to the amount of regular reads and writes on your average system, you'll save under 1% of the writes by adding a fast ZIL. And remember, the ZIL is just a write log. Everything that gets written to it will get flushed to disk when zfs writes the next transaction group. -- Dan Nelson dnel...@allantgroup.com _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"