From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: References: <4E01F311.3060305@0x6a.com> <20110623104644.5cd888d7@wks-ddc.exosec.local> <4E0352E9.9050600@0x6a.com> <201106231725.10215.dexen.devries@gmail.com> Date: Thu, 23 Jun 2011 09:28:49 -0700 Message-ID: From: ron minnich To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: [9fans] Survey: Current Fossil+venti Filesystem Topicbox-Message-UUID: f4f28004-ead6-11e9-9d60-3106f5b1d025 On Thu, Jun 23, 2011 at 9:19 AM, erik quanstrom wro= te: > i don't think this paper applies to write-once systems like > venti (or ken fs for that matter). but it might apply to fossil. > also, good ssds are rated in terms of a minimum amount of data > that can be written to them. =A0an very good ssds have a minimum > write number that means they can be written to at maximum speed > for the drive's full rated lifetime. The main point I took from the talk they gave was that failure was most strongly related to the number of writes in FLASH. If your striping strategy is to duplicate writes to each drive, you faced the happy prospect of doing a write and having both drives fail at the same time. Hard drives have a different way of failing. We've seen weirdness like this here, with drives in a bunch of nodes that all seem to fail simultaneously, well within rated lifetime. Not cheap drives either. Of course that was a little while ago and things seem to have gotten better, but it's worth a warning. Anyway, it's important to keep in mind that SSDs are a bit different. ron