Date: Fri, 4 Nov 2005 01:09:10 +0200 From: Brad Knowles <brad@stop.mail-abuse.org> To: Dan Nelson <dnelson@allantgroup.com> Cc: Francisco Reyes <francisco@natserv.net>, stable@freebsd.org Subject: Re: Disk 100% busy Message-ID: <p06200765bf9048b1947d@[10.0.1.210]> In-Reply-To: <20051103200627.GD67512@dan.emsphone.com> References: <0E972CEE334BFE4291CD07E056C76ED807738005@bragi.housing.ufl.edu> <p06200716bf78aa876114@[10.0.1.210]> <20051103133248.Y60367@zoraida.natserv.net> <436A5B7D.6090408@mac.com> <20051103143332.B60864@zoraida.natserv.net> <20051103200627.GD67512@dan.emsphone.com>
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At 2:06 PM -0600 2005-11-03, Dan Nelson wrote:
> The biggest reason for going RAID-5 is that you only get 50% useable
> capacity out of RAID 10, and at least 75% out of a RAID 5 (with a 3+1
> layout. With an 8+1 layout you get 88%). If you don't need fast
> writes, or your controller has sufficient cache to mask the write
> penalty, RAID 5 sure holds a lot more data on the same disks.
However, with RAID-5 you're in seriously bad shape when one of
the disks dies. You really need to add a hot spare to that list.
And intelligent controllers can be used with other RAID types, too.
--
Brad Knowles, <brad@stop.mail-abuse.org>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/>; for more info.
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