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Posted by Tony Rogerson on 10/02/08 11:46
Are you absolutely absolutely absolutely sure the disk write cache on both
machines was set the same?
RAID 10 will always out perform RAID 5 on read performance in a real
situation because it has 2 copies of the data it can concurrently read. When
writing to disk RAID 5 needs to read as well in order to calculate parity.
There is just so much to doing the comparison....
--
Tony Rogerson
SQL Server MVP
http://sqlserverfaq.com - free video tutorials
"Dave" <daveg.01@gmail.com> wrote in message
news:1146510578.745595.255290@g10g2000cwb.googlegroups.com...
> RAID 5 beats RAID 10
>
> Can I get some feedback on these results? We were having some serious
> IO issues according to PerfMon so I really pushed for RAID 10. The
> results are not what I expected.
>
> I have 2 identical servers.
>
> Hardware:
> PowerEdge 2850
> 2 dual core dual core Xeon 2800 MHz
> 4GB RAM
> Controller Cards: Perc4/DC (2 arrays), Perc4e/Di (1 array)
>
> PowerVault 220S
> Each Array consisted of 6-300 GB drives.
>
> Server 1 = Raid 10
> 3, 6-disk arrays
>
> Server 2 = Raid 5 (~838 GB each)
> 3, 6-disk arrays (~1360 GB each)
>
> Test Winner % Faster
> SQL Server - Update RAID 5 13
> Heavy ETL RAID 5 16
> SQLIO - Rand Write RAID 10 40
> SQLIO - Rand Read RAID 10 30
> SQLIO - Seq Write RAID 5 15
> SQLIO - Seq Read RAID 5 Mixed
> Disktt - Seq Write RAID 5 18
> Disktt - Seq Read RAID 5 2000
> Disktt - Rand Read RAID 5 62
> Pass Mark - mixed RAID 10 Varies
> Pass Mark -
> Simulate SQL Server RAID 5 1%
>
> I have much more detail than this if anyone is interested.
>
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