RE: Raid Solution -- MIDRANGE-L

Matthias Oertli wrote:

        We have a 9402-400 with 3 6607 (4GB) disks, currently
unprotected. I finally 
        got the go-ahead (budget) to implement RAID.
        I would just like to ask a few questions to see if I got this
right, so here goes: 

        Q1. Because we're at v3r7 the loadsource must be mirrored and
the other two disks 
        'raided'. Right or wrong?

        A1. Wrong - The loadsource must be mirrored but you need a
minimum of 4 disks in a RAID array.

        Q2. In order to keep 12GB of diskspace available I need to get
three additional 
        6607's. Right or wrong?

                A2. Right - You must have a total of 6 disks in this
configuration.  Two 6607's mirrored of the MFIOP and
                4 6607's RAIDed of the new 6522 disk controller.  This
will give you 16GB usable capacity.

        Q3. The way I understand it, my existing three disks are
currently connected via 
        the MFIOP (rather than a dedicated disk controller) which is a
performance 
        bottleneck. Right or wrong?

                A3. Yes your disks are connected via the MFIOP.  I am
not sure if this is a bottleneck.  Typically memory 
                or processor could be a greater bottleneck in some
systems.

        Q4. The IBM-reseller is quoting the 6522 raid controller. Are
there different (from a 
        performance point of view) raid controllers I should consider?

                A4. The 6522 is the standard RAID controller for your
configuration.  It replaces the older 6502.

        Q5. Assuming that the new raid controller will connect to all
disks, can I expect a 
        performance increase regardless of the raid overhead (because
the MFIOP is 
        out of the picture)?

        A5. The new RAID controller will attach to 4 of the 6 disks.  I
wouldn't expect a major performance
        increase unless you currently have a disk bottleneck.  If you
have performance tools on your system
        (5716-PT1) you could get some stats regarding your current disk
performance.

        Q6. Does the amount of main storage (ram) used by the system
increase with raid? 

                A6. I don't know.  I wouldn't have thought so as RAID is
implemented via hardware (the 6522)

        Q7. Should I look at adding some ram (currently 160MB)?

                A7. 160MB should be OK.  Again, performance tools could
highlight any problems is this area.
                Alternatively, WRKSYSSTS and look at the storage pool
stats

        IMO, you should look at RAID to protect your system against a
single disk failure.  This is the primary 
        reason for implementing RAID.

        By the way,  if you do not currently have the 7117 expansion
unit, you will have to purchase one of these
        to house the additional disks.

        The features yuo will require are :

        1 x 6522 disk unit controller
        3 x 6607 4GB disk units
        1 x 7117 integrated expansion unit

        Good luck

        Regards

        Chris Cole
        chrisc@itexjsy.com

                
+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to "MIDRANGE-L@midrange.com".
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---