In article <[log in to unmask]>, [log in to unmask] says...
>
>In article <[log in to unmask]>,
<snip>
>>>2- Better resiliency.  If you have multiple UVS (User Volume Sets) you are
>>>less hurt when you throw a disc (so to speak).  If the disc is part of SVS
>>>(MPE_XL_SYSTEM_VOLUME_SET) you may be faced with an INSTALL but only for
that
>>>(relatively) small volume set.  If the disc is part of a UVS, then only that
>>>volume set goes down, the rest stays up.  You can then deal with that UVS
>>   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>while the other UVS' remain unaffected.
>>
>>I beg to differ, I have experienced situations  where a Private Volume drive
>>has failed and brought down the whole system. Also, the whole system has been
>>brought down by merely attempting to purge a corrupt file on a PVS.
<snip>
>Secondly, the main purpose of private volumes is to protect user data.  Some
HP
>reps are misinformed and will tell you that private volumes will significantly
>improve your uptime by eliminating downtime due to disk failures.  This is not
>true since the HP/3000 will allow users to continue to hold critical system
>resources while they are waiting for a volume set to go back on-line.  And as
>long as they hold these critical resources (e.g. the file integrity SIR or
even
>a simple database lock) other users will continue to hang behind them.  Also,
>remember that while these users hold critical resources, they are also
>unabortable.
>
>I would like to also say, that as long as you use private volumes for data
>protection, you will not be disappointed.  Just don't try to use private
volumes
>
>to increase your uptime, you will be disappointed.
>
>
>-------------------------------------------------------------------
>Michael P. Smith                        [log in to unmask]
>HP Sr. Systems Programmer               [log in to unmask]
>Hertz Corporation, Oklahoma City, OK
>-------------------------------------------------------------------
<snip>
 
It is true that a failure on a User Volume will hang the system.  However,
while you are
placing the call to HP and waiting for the CE to arrive and repair the drive,
you can bring
the system back up and allow the users not affected by the down volume set to
run.
 
Of course, when HP arrives you will once again have to =SHUTDOWN the system.
After the
drive is replaced and the system is back up, you can once again let a portion
of the users
back on while you RESTORE the files from the failed volume set.
 
If the failure is on the system volume set, the recovery time is also
decreased.  (But I
think that was already meantioned.)  I do not know if anyone meantioned the
advantage of
non-system volume sets having their own Transaction Manager(XM) logfiles.  This
increases
transaction throughput by spreading the load.
 
We also use non-system volume sets to separate our Oracle logfiles from our
Oracle data.
This increases our chances sucessful recovery in the event of a disc crash.
 
Another 'must use' situation for non-system volume sets is when you add a disc
array(RAID)
to your system.  It makes no sense at all to add a RAID disc to the same volume
set as a
non-redundant disk.
 
Mark Ranft
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