[libvirt-users] Performance tuning questions for mail server

[Emmanuel Noobadmin]

On 10/10/11, Alex <mysqlstudent at gmail.com> wrote:
> I thought RAID10 still involved RAID1 on all disks, so really the only
> improvement would be the lack of the parity write, correct? The
> wikipedia entry seems to indicate it's not all that much faster:

Parity write and parity calculations. For a RAID 1 or RAID 10 setup,
you just write the same data to 2 disks. But for RAID 5, you need to
read, verify parity, calculate new parity, then write.
In terms of raw sequential bandwidth, the two don't differ that much
but it's the random IOPS that's the problem.

You can check out this post, it's meant for an Exchange 2007 server
but the calculations there clearly demonstrate the difference between
RAID 1/10 and RAID 5, it also assumes a 50/50 mix.

http://www.mmcug.org/blogs/Lists/Posts/Post.aspx?ID=16

There are also plenty of other tests and articles done to compare RAID
10 and RAID 5.