Joe,

You are correct.  It would be best, in a production environment, to have at
least 3-4 spindles in the system volume set.  The main reason for this is
for the system to have adequate space and spindles to spread out transient
disk I/O's (e.g. swapping-related disk I/O's).  The more disk I/O you have
on the system, the greater the benefit in parallelizing these I/O's.

Also, many shops put more than just MPE-related stuff in the system volume
set.  This means that it is increasingly difficult to keep enough free
space in a single disk system volume set, especially since you generally
have only 75 percent of the disk capacity available for permanent disk
files anyway.  (The 75 percent number is the default setting for permanent
disk allocation on ldev 1.  I have been able to change this number to
upwards of 87% without ill effect but I recommend that you leave it at 75%
because it tweaks some of the RC people when they see it.  Besides, don't
be a cheapskate!)

Bill Lancaster

At 12:00 PM 10/27/98 +0000, Joe Alexander wrote:
>This raises a slightly tangential issue - I have always understood  that
>when possible a system should have multiple (3-4?) spindles in the sys
>volset, presumably due to i/o which is restricted to that vs. I have 3 small
>systems  configured this way even though I'd be more comfortable with
>most of the drives in non-sys volsets. Am I mistaken?
>
>Joe Alexander   Systems Manager
>Biowhittaker, Inc.  Walkersville MD
>[log in to unmask]
>
>>>> "[log in to unmask]" 10/27/98 09:39am >>>
>I need advice from the MPE gurus -
>I am running an HP 979 with MPE 5.5 PP3. I have only disc 1 configured
>as MPEXL_SYSTEM_VOLUME_SET
>and the rest of the discs are configured as private volumes (or
>non-system volumes).
>I have only recently started building files in HFS space and found that
>they may reside only in  the system domain.
>I guess, it makes some sense, since HFS is not restricted to the acount
>structure.
>Is there any way to force an HFS file to reside on private volume ?
>TIA, Olek.
>
>