On Tue, Mar 09, 2010 at 04:54:44PM -0600, John G. Heim wrote: > Has anyone configured a database server with RAID-5? Is it really a bad idea > to do so? I asked last month for tips on configuring a DB server. I have > around $6K to spend. I am pretty much settled on getting 2 quad-core CPUs > and 32 Gb of RAM. But I'm still ignorant in terms of what to get for disk. > 1500 RPM, I know that. But is it better to do RAID-1 or RAID-5. I can't > figure out why RAID-1 would be better than RAID-5. I understand that with > RAID-5, a single database write might translate into writing 2 blocks (a > data block and a parity block). But doesn't RAID-1 *always* do an extra > write for every data block written?
RAID 5's problem isn't the extra write. It's that to write a hunk that's not a whole stripe width (64k * (num_drives - 1)) it has to first read a whole stripe (num_drives-1), calculate the parity, and then write to 2 disks. -- Matt Domsch Technology Strategist, Dell Office of the CTO linux.dell.com & www.dell.com/linux _______________________________________________ Linux-PowerEdge mailing list Linux-PowerEdge@dell.com https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq
