Promise RAID-1 vs software RAID-1

[Brian Gaynor]

On Wed, 2004-06-16 at 11:02, Lucas Harms wrote:

> Since a raid 1 is only about security, I doubt a proper raid 1 setup would
> allow you to read from both drives.  There is the possibility that through
> some bug, a write and read could occur at the same time if the drives are on
> different ide controllers.

According to the Software RAID howto RAID-1 write performance may suffer
due to the redundant writes, but read performance does benefit from the
software RAID reading from the disk whose heads are closest to the data.
In my experience with RH9/FC1 software RAID-1 the read performance is
better than non-RAID with the same disks (almost 40% as measured by
hdparm). 

The two drives used in this RAID array are on separate IDE interfaces.
This is primarily because a drive failure will often take out that IDE
interface, so using separate interfaces is more reliable. 

-- 
Brian Gaynor
Precision MicroControl Corp.

  e-mail: briang at pmccorp.com
     web: http://www.pmccorp.com
   phone: 760.930.0101
  direct: 760.930.0485 x13
     fax: 760.930.0222