From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <75bd45f10fe4970a189c6824bbadc841@quanstro.net>
From: erik quanstrom <quanstro@quanstro.net>
Date: Mon, 21 Sep 2009 16:30:25 -0400
To: 9fans@9fans.net
In-Reply-To: <20090921191005.DD14F5B55@mail.bitblocks.com>
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Subject: Re: [9fans] Petabytes on a budget: JBODs + Linux + JFS
Topicbox-Message-UUID: 73e9a574-ead5-11e9-9d60-3106f5b1d025

> > 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.

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.

- erik