RAID10+10Krpm vs RAID5+15Krpm

On Wed, 14 Jan 2004 17:19:32 GMT, Aaron Couts <spam DeleteThis @couts.org> wrote:

 >I'm setting up a SCSI drive array, and I was wondering, which is more
 >significant -- RAID level or drive speed? I'm considering the following
 >setups:
 >RAID 10 with 10K rpm drives
 >RAID 5 with 15K rpm drives
 >
 >Obviously RAID 10 will always have the advantage of greater redundancy,
 >but I've never had two drives fail at the same time, and with RAID 5
 >I could probably afford a hotspare.
 >
 >Anyone been able to compare the speeds of these two setups? My machine
 >is a heavily loaded database server with roughly twice as much read
 >activity as write activity.

For enterprise servers a RAID10 array with lots of spindles is usually
assumed to be the fastest solution for databases.
Of course the question remains whether that is more than the extra
performance of the 15k drives.

Still you have quite a lot of write activity, so I think that Raid10
would be the fastest.

But are the logdrives included in that write activity? In that case
you might want to use a seperate disk or seperate RAID1 volume for the
logdrives.
If you database then mainly has read activity you can use Raid5 for
the database itself.

Also you should tru to maximize the numbers of harddisks in your
array. A database usually has mostly random reads and writes, and
performance of that will be increased if you use more harddisks in the
array. So if you have the room in your server/enclosure, use a large
number of smaller disks instead of a smaller number of large disks.

You will find this article interesting:
<a style='text-decoration: underline;' href="http://www1.us.dell.com/content/topics/global.aspx/power/en/ps3q99_raid?c=us&l=en&s=esg" target="_blank">http://www1.us.dell.com/content/topics/global.aspx/power/en/ps3q99_rai...=us&l=e</a>

Also a little test here from someone who tested raid5 and raid10 on
MySQL: <a style='text-decoration: underline;' href="http://www.johnleach.co.uk/documents/benchmarks/raidperf.html" target="_blank">http://www.johnleach.co.uk/documents/benchmarks/raidperf.html</a>

Marc<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: RAID10+10Krpm vs RAID5+15Krpm 

In article <rkmc00ldu5u6jnsebqmaflstat7ou2481p DeleteThis @4ax.com>, Marc de Vries wrote:
 > On Wed, 14 Jan 2004 17:19:32 GMT, Aaron Couts <spam DeleteThis @couts.org> wrote:
 >
  >>I'm setting up a SCSI drive array, and I was wondering, which is more
  >>significant -- RAID level or drive speed? I'm considering the following
  >>setups:
  >>RAID 10 with 10K rpm drives
  >>RAID 5 with 15K rpm drives
  >>
 > But are the logdrives included in that write activity? In that case
 > you might want to use a seperate disk or seperate RAID1 volume for the
 > logdrives.
 > If you database then mainly has read activity you can use Raid5 for
 > the database itself.

Thanks for your very helpful response and links. I think we're going to
do both -- a RAID10 for the logfiles and some of the data, and a RAID5
for indexes. We have everything on a single a RAID10 now.

-Aaron

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 >> Stay informed about: RAID10+10Krpm vs RAID5+15Krpm