Date: Tue, 13 Nov 2012 23:03:58 -0600 From: Chris BeHanna <chris@behanna.org> To: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: SSD recommendations for ZFS cache/log Message-ID: <B56BFD5B-69BD-442F-96C3-412C88812AF1@behanna.org> In-Reply-To: <50A31D9A.7020200@shatow.net> References: <CAFHbX1K-NPuAy5tW0N8=sJD=CU0Q1Pm3ZDkVkE%2BdjpCsD1U8_Q@mail.gmail.com> <57ac1f$gf3rkl@ipmail05.adl6.internode.on.net> <943159E4-8824-4767-96E1-89E8EC69DCDF@behanna.org> <50A31D9A.7020200@shatow.net>
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On Nov 13, 2012, at 22:27 , Bryan Drewery <bryan@shatow.net> wrote: > On 11/13/2012 10:18 PM, Chris BeHanna wrote: >> On Nov 13, 2012, at 21:51, Stephen McKay <smckay@internode.on.net> = wrote: >>=20 >>> [...lots of good advice about measuring, and lots of good advice = about L2ARC...] >>>=20 >>> I have no way to determine in advance the behaviour of an SSD on >>> power failure so I assume all the ones I can afford have bad >>> behaviour. :-) I know that expensive ones contain capacitors so >>> that power failures do not corrupt their contents. By the nature >>> of advertising (from which we know that any feature not excessively >>> hyped must therefore not be supported), we must conclude that other >>> SSDs by normal operation corrupt blocks on power failure. >>=20 >> If you'll pardon what may be an ignorant question, does this matter = if you have your machine on a UPS, especially if you run upsmon or nut = to do a graceful shutdown when there are n minutes of battery remaining? >=20 > I've had more than 1 UPS battery die on me, resulting in instant = shutoff. Mine always die at 0300 or thereabouts, and none of my UPSen has = an "I know, now STFU" button. I would gather that the extra expense of a capacitor-backed SSD = if you already have a UPS (with relatively new batteries) depends upon = the particular use case. Banking data? Hell yeah. Home office? Meh. = I might lose a few pieces of spam and the last few minutes of work from = my text editor. --=20 Chris BeHanna chris@behanna.org
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