>Mark Landin wrote:
>
>>
>>Any time you *remove* a volume from MPEXL_SYS....SET, you must do a reload.
>>That's because, unlike private volume sets, directory and account information
>>for MPEXL...SET is spread among all members of the volume set. So if you take
>>even one member away...you must RELOAD.
>>
>

Pete Crosby wrote:

>It goes further than that. Any time you remove a volume from ANY volume
>set, you must rebuild the set from scratch. In the case of the system
>volume set that means an INSTALL. In the case of a user volume set,
>you scratch the other volumes and recreate the set.
>
>--
>                            --Pete Crosby
>                              [log in to unmask]
>
>

Not to put to fine a point on it, let's restate this just to be clear.  If
you remove a volume from a user volume set, you must, in effect, reload that
complete user volume set.  I have seen lots of sites where the system volume
set had a few drives and there was a single user volume set with many
drives.  One customer has 6 drives in the system volume set and probably
close to a hundred in a single user volume set.  While they wouldn't have to
actually perform an INSTALL to take a drive from that set, for all intents
and purposes they will spend nearly the same amount of time reloading.

The moral of this story is that all your woes won't be over if you move to
user volumes (which I highly recommend from performance and operational
points of view) but that if properly designed and managed, they will add
significant flexibility as well as performance improvement.

BTW, be sure to leave plenty of disk space, and spindles, for the system
volume set.  I have a customer right now who has 40 drives in user volumes
sets and 1 (!) for the system volume set.  They are wondering why their I/O
performance is suffering...


Bill Lancaster
Lancaster Consulting
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