Re: more DASD!!!

[Douglas Handy <dhandy1@xxxxxxxxxxxxx>]

Dan,

>Is the maximum counting only the "usable" mirrored DASD or the total DASD
>regardless of mirroring?  

It is the maximum of 4 drives on the FSIOP plus 8 drives in the 7117 expansion
feature.  Twelve drives at 4.19 each gives about 50.3GB (max unprotected).

On your box, the FSIOP drives cannot be part of a RAID set, so those should both
be mirrored pairs.  On the 7117, you can put all 8 drives in a RAID set, so the
maximum protected DASD you can reach is:

  2 x 4.19 =   8.38  mirrored drives in the FSIOP
  7 x 4.19 = 29.33  effective usable area of RAID 8 drive set
                  ----------
                   37.71 GB maximum protected DASD

Using all mirrored pairs, you'd be reduced to 6 pairs @ 4.19 = 25.14GB or so.

In your current case, you can either add 4 drives in a RAID set, increasing your
DASD by about 12GB, or you can change the 4 drives in the 7117 to be part of a
new RAID set.  RAID sets need at least 4 drives per set, and the 7117 only has
room for 8 drives but they could all be in the same set.

I know the 6502/6522 controller you'd have in the 7117 can handle two RAID sets.
I am not sure if it can do two mirrored pairs *plus* a RAID set.  So it may not
be possible to add a RAID set and leave the existing 4 drives mirrored.

OTOH, without even buying another drive you could convert the 4 mirrored drives
(in the 7117) to a RAID set and pick up another 4.19GB usuable space, which
gives you a 25% boost in capacity without buying more drives.  And you'd still
be protected from drive failures.

The 400-2133 does not have hot swappable drives anyway, and for a machine likely
to  be retired within a year I'd convert to RAID and add only as many drives as
you need.  For example, buying one more 6607 and converting to RAID will give
you a 50% increase in protected DASD from your current config.

>A concern was raised that whatever additional DASD we buy today for this old
>box might not be migratable to any new iSeries system we acquire in the
>future.  Is that a real concern?  

I *think* support for the 6607 drives is going (has gone?) away on newer models.

But the newer drives are faster anyway.  The 6607's aren't expensive enough to
warrant taking to the next machine when you only have 8-10 of them.

IMHO.

Doug

+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@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
+---