From mboxrd@z Thu Jan 1 00:00:00 1970 To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> In-reply-to: Your message of "Mon, 21 Sep 2009 16:30:25 EDT." <75bd45f10fe4970a189c6824bbadc841@quanstro.net> References: <75bd45f10fe4970a189c6824bbadc841@quanstro.net> From: Bakul Shah Date: Mon, 21 Sep 2009 15:07:48 -0700 Message-Id: <20090921220749.08F7E5B60@mail.bitblocks.com> Subject: Re: [9fans] Petabytes on a budget: JBODs + Linux + JFS Topicbox-Message-UUID: 73f6bd2c-ead5-11e9-9d60-3106f5b1d025 On Mon, 21 Sep 2009 16:30:25 EDT erik quanstrom wrote: > > > i think the lesson here is don't by cheep drives; if you > > > have enterprise drives at 1e-15 error rate, the fail rate > > > will be 0.8%. of course if you don't have a raid, the fail > > > rate is 100%. > > > > > > if that's not acceptable, then use raid 6. > > > > Hopefully Raid 6 or zfs's raidz2 works well enough with cheap > > drives! > > don't hope. do the calculations. or simulate it. The "hopefully" part was due to power supplies, fans, mobos. I can't get hold of their reliability data (not that I have tried very hard). Ignoring that, raidz2 (+ venti) is good enough for my use. > this is a pain in the neck as it's a function of ber, > mtbf, rebuild window and number of drives. > > i found that not having a hot spare can increase > your chances of a double failure by an order of > magnitude. the birthday paradox never ceases to > amaze. I plan to replace one disk every 6 to 9 months or so. In a 3+2 raidz2 array disks will be swapped out in 2.5 to 3.75 years in the worst case. What I haven't found is a decent, no frills, sata/e-sata enclosure for a home system.