Date: Thu, 3 Nov 2005 14:06:27 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Francisco Reyes <francisco@natserv.net> Cc: stable@freebsd.org Subject: Re: Disk 100% busy Message-ID: <20051103200627.GD67512@dan.emsphone.com> In-Reply-To: <20051103143332.B60864@zoraida.natserv.net> 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>
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In the last episode (Nov 03), Francisco Reyes said: > On Thu, 3 Nov 2005, Chuck Swiger wrote: > How about for database? In particular postgresql. > How bad would RAID 5 be for it? > > I still have some, limited, hopes I can convince the owner of the > company to go with RAID 10 with 10K rpm drives.. the most likelyhood > we will go with RAID 5, 7200rpm drives for a database project ahead. > Alternatively I will see how RAID 5 with 10K rpm SCSI drives compares > price wise, but I am sure it will be substantially more. :-( 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. Always keep your logs on a separate mirrored set of disks, of course. -- Dan Nelson dnelson@allantgroup.com
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