Date: Mon, 14 Feb 2011 15:32:30 -0800 From: Chuck Swiger <cswiger@mac.com> To: David Brodbeck <gull@gull.us> Cc: Frank Shute <frank@shute.org.uk>, FreeBSD <freebsd-questions@freebsd.org>, Maxim Khitrov <max@mxcrypt.com> Subject: Re: FreeBSD and SSD drives Message-ID: <7583C9E5-EA30-4C75-BDF7-C1BA123B8334@mac.com> In-Reply-To: <AANLkTinGpj1Eb2FAybP%2BDOWUs48LeHC0d6=bMRZbby%2Bx@mail.gmail.com> References: <AANLkTin%2BexaH5ORk9zAYsWoUzVtyCWcv3unpJRUK46FV@mail.gmail.com> <AANLkTi=AjHG5trQqOAHnVT4Ki9ORxF_ynm7MHsLiF_9h@mail.gmail.com> <20110213073814.GC57674@guilt.hydra> <AANLkTim-u5Nd8NQ_t555o5qYwRd5Ltf6Ud5rYD_G2x7N@mail.gmail.com> <20110213092353.GA58281@guilt.hydra> <20110213073801.65518b9c@scorpio> <20110213131051.00001ebf@unknown> <20110213085805.72f0132d@scorpio> <20110213164748.GB60459@guilt.hydra> <AANLkTi=NOUgFC3iOesKkb9%2BgLEpAAKdvcMh8Am99im%2Bi@mail.gmail.com> <20110213181223.GD55168@orange.esperance-linux.co.uk> <AANLkTinGpj1Eb2FAybP%2BDOWUs48LeHC0d6=bMRZbby%2Bx@mail.gmail.com>
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Hi-- On Feb 14, 2011, at 3:17 PM, David Brodbeck wrote: > I would be curious to hear stories from people who actually *have* run > into SSD failures related to write limitations. I've heard a lot of > speculation but no actual anecdotes. I'm sure they're out there; but > I also know people are more likely to complain when things go wrong > than talk about things going right, so my suspicion is it must be > rare. Back around 2005 / 2006, we were using a bunch of Soekris 4511's, IIRC, running NetBSD and a network IDS we'd been working on, which possibly generated 100s of MB to a few GB of logging per day. Whoever did the initial setup didn't realize that the flash cards of that timeframe were limited to 10K writes or so, and after a few months you started getting 16K chunks of old logfile data, or 16K chunks of new and old logfile data corrupted together-- looked to be a binary OR of the 0 bits. Nothing reported that writes were failing-- evidently the flash cards didn't notice an error and thus didn't report it back to the system. Switching /var to tmpfs resolved the issue for us. >From what I understand (a quick review of wikipedia helps :), modern flash cards are now typically rated for 100K writes, include ECC bits to actually correct or at least detect errors and try to remap bad blocks to unused blocks, and implement wear-leveling techniques of varying degrees of effectiveness. Regards, -- -Chuck PS: Reposted from a NetBSD thread, was <D5AF2A8E-FEF0-467E-BE4A-B01243E21F1A@mac.com>....
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