Date: Sat, 11 Jul 2009 13:07:52 -0700 From: Freddie Cash <fjwcash@gmail.com> To: freebsd-stable@freebsd.org Subject: Re: ZFS - thanks Message-ID: <b269bc570907111307y6d0f33a8g440a0f7d34367260@mail.gmail.com> In-Reply-To: <20090711084042.GA77702@server.vk2pj.dyndns.org> References: <20090709112512.GA44158@hugo10.ka.punkt.de> <73a41d4b72d62b0bfe3d0fb7206376a8.squirrel@cygnus.homeunix.com> <cf9b1ee00907090525t7a337775q71aa01e6a3173de5@mail.gmail.com> <84665df87e93a6ccf24d9837cbc53eba.squirrel@cygnus.homeunix.com> <cf9b1ee00907090539i70bf97eq32fe0aa960e9dc52@mail.gmail.com> <20090711084042.GA77702@server.vk2pj.dyndns.org>
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On Sat, Jul 11, 2009 at 1:40 AM, Peter Jeremy <peterjeremy@optushome.com.au>wrote: > On 2009-Jul-09 15:39:35 +0300, Dan Naumov <dan.naumov@gmail.com> wrote: > >A single 40 disk raidz (DO NOT DO THIS) will have 40 disks total, 39 > >disks worth of space and will definately explode on you sooner rather > >than later (probably on the first import, export or scrub). > > Can you provide a reference for this statement. AFAIK, the only > reason for the upper recommended limit of 9 disks is performance. > We found it impossible to re-silver a new/replacement drive in a 24-drive raidz2 vdev. Even after almost two weeks of trying, it never got above 20-30% complete before restarting. That led me to do a bunch of web searches, and found several blogs by Sun people that went over how the raidz implementation works, what the limitations are (limited to the IOps of a single drive), and the recommendation to never use more than 8 or 9 drives in any single vdev. -- Freddie Cash fjwcash@gmail.com
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