Date: Mon, 27 Jun 2011 11:56:47 +0200 From: Damien Fleuriot <ml@my.gd> To: Joshua Isom <jrisom@gmail.com> Cc: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: Performance of a USB ZIL for ZFS Message-ID: <4E0853DF.1080407@my.gd> In-Reply-To: <4E06C2D1.4050601@gmail.com> References: <4E06180F.7090409@gmail.com> <16AE025C-EA55-45F3-8419-542228CE5AA4@my.gd> <4E06C2D1.4050601@gmail.com>
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On 6/26/11 7:25 AM, Joshua Isom wrote: > On 6/25/2011 9:32 PM, Damien Fleuriot wrote: >> On 25 Jun 2011, at 19:17, Joshua Isom<jrisom@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. >>> _______________________________________________ >>> freebsd-questions@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >>> To unsubscribe, send any mail to >>> "freebsd-questions-unsubscribe@freebsd.org" >> >> >> 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. What do you want to do here, data security or performance ? Having a dedicated ZIL is accepted to be a performance concern, more than security. Obviously you'll do as you please, but I'll tell you what: If you're going to play cheap and grab a USB key for your ZIL, don't be surprised when you lose your data and/or experience downtime because your key went boom, or the USB controller hung for a sec and your sync failed. This is data we're talking about, and considering you want a dedicated ZIL this is probably important and/or voluminous data.
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