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From:Dan Nelson Date:March 10 2010 5:04pm
Subject:Re: mysql & RAID
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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
	dnelson@stripped
Thread
mysql & RAIDJohn G. Heim10 Mar
  • Re: mysql & RAIDDan Nelson10 Mar
    • Re: mysql & RAIDWm Mussatto10 Mar
  • Re: mysql & RAIDGlyn Astill11 Mar
  • Re: mysql & RAIDЕвгений Килимчук16 Mar
    • Re: mysql & RAIDJohn Daisley16 Mar