On Wed, March 10, 2010 09:04, Dan Nelson wrote: > In the last episode (Mar 10), John G. Heim said: >> I have read (and have been told) to stay away from RAID-5 for >> update-intensive systems. Are there performance concerns with RAID-10 >> as >> well? We will be buying from Dell (done deal for reasons too >> complicated >> to go into) and the disks they're selling are 146 Gb. I can get up to 8 >> of them in the server we're buying. I asked them about just getting 2 >> big >> disks and going with RAID-1. >> >> My understanding is that with RAID-10, the system can do multiple reads >> and >> writes simultaneously so throughput is improved oversystems w/o RAID or >> with >> RAID-1. But the same logic would apply to RAID-5 only it doesn't work >> out >> that way. > > RAID-5 has an extra penalty on small random writes due to the I/O required > to maintain the parity blocks (it does 2 reads and 2 writes for every > write > your app does). RAID-10 is just a mirror so it doesn't have to worry > about > that. > > -- > Dan Nelson > dnel...@allantgroup.com > If you can get the disk cheap you might want to get one or two extras and keep them as spares.
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