Performance of a USB ZIL for ZFS

[Joshua Isom]

On 6/25/2011 9:32 PM, Damien Fleuriot wrote:
> On 25 Jun 2011, at 19:17, Joshua Isom<jrisom at 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.
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>
>
> 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.