At 12:35 PM 11/02/1999 -0700, Karl Hancock wrote:

>I am wondering what experience is out there regarding the performance of
>HP's 12H disk array using Raid level 5?  I understand that there is a
>performance hit when you want fault tolerance or high availability but I am
>just wondering how much the hit is.

I posted the following on this subject on 10/14/99:

>Sorry for the delayed response to your questions.  I have been working with
>the AutoRAID devices on MPE for a number of months now with one particular
>customer.  As with any technology, there is a good side and a bad
>side.  The good side of the 12H is that it will ultimately be the most
>highly available high availability choice for the money on MPE.  This is
>taking into account price, performance, RAID technology, etc.  The bad side is
>(as with any high availability choice) there is a potential performance
>penalty.  Also, though this element will go away with time, "official"
>support is for 6.0 and not 5.5.  The reason for this is that the current
>AutoRAID Manager (ARM) software runs natively on 6.0.  If you run on 5.5
>you need to have a separate NT server, with a SCSI connection, to manage
>those boxes.  Not an ideal situation.
>
>There isn't a lot of good performance information about AutoRAID on MPE,
>and probably won't be for some time.  The main reason for this is that the
>12H is highly configurable so, unlike Mirrored Disk/iX for example, the 12H
>performance characteristics will vary widely from site-to-site.  It's
>likely to be some time before there are a large number of these devices in
>the community.
>
>That all being said, I'm very happy with how the 12H's are working at my
>client's site.  We are running, I think, seven fully populated boxes there,
>in a variety of environments.  We are preparing to move these into the
>primary production environment in the next several weeks.
>
>Regarding your question about the 9.1 gb drives.  I believe that these are
>the 7200 rpm drives.  There is an option for 10,000 rpm 9 gb drives.  I
>highly recommend the 10k drives.  You can also get the 18gb 10,000
>drives.  Choosing which depends on your environment.  If you are running a
>highly spindle-sensitive application, more spindles (even if the mechs are
>somewhat slower) is desirable.  If you require large amounts of data, with
>a minimal OLTP performance requirement, larger, denser drives may be the
>best way to go.

<snip>

>Also, what high availability disk drives can be used for Ldev1?
>

You can easily obtain used Disk Arrays (model 10/model 20) that work just
fine, IN RAID 1 ONLY, as the system volume set.  However, you can use
AutoRAID for the system volume set as well.

Regarding RAID 5, let me say again that I strongly oppose having RAID 5 as
a production volume set technology in mission critical environments.  Not
every one agrees with this statement but I've see enough serious
performance problems to strongly advise people away from RAID 5 in
production.

Bill Lancaster