Re: Performance of a USB ZIL for ZFS
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 Isomjri...@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-unsubscr...@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. ___ 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
Re: Performance of a USB ZIL for ZFS
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 Isomjri...@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
Re: Performance of a USB ZIL for ZFS
On 25 Jun 2011, at 19:17, Joshua Isomjri...@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. You question is a good one, but I think the reason for your question may be off. If you want the ZIL in a separate location it is to cut down on latency rather than thrashing. See: http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Disabling_the_ZIL_.28Don.27t.29 If your concern really really is thrashing please consider the cost of flash memory vs a hard drive. Replacing a bad hard drive is cheaper. After a cursory glance at newegg, you can see the price per MB for: HDD $0.09 USB flash $0.64 SSD $1.875 ___ 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
Performance of a USB ZIL for ZFS
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-unsubscr...@freebsd.org
Re: Performance of a USB ZIL for ZFS
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. ___ 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 I stopped reading at the title. The answer is no. Grab a SSD for $80-120ish.___ 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
Re: Performance of a USB ZIL for ZFS
On 6/25/2011 9:32 PM, Damien Fleuriot wrote: On 25 Jun 2011, at 19:17, Joshua Isomjri...@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-unsubscr...@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. ___ 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
