09-10-2007 04:01 AM
Solved! Go to Solution.
09-11-2007 03:06 AM
I have seen a number of cases where the data is on the EMC but the MPE volume set is on a nike array.
09-11-2007 04:32 AM
i'll throw out a thought....in *nix-land, it can be problematic to control the order of what devices get recognized when upon reboot. since internal devices are going to be seen before external...there is a strong tendency for disc containing the OS to be internal.
with that being a prevailing thought, it's easy to see where confusion may enter mpe-land.
09-11-2007 05:31 AM
internal disks, MPEXL_SYSTEM_VOLUME_SET, and EMC.
The reason internal disks seemed to be seen
first is that they're usually at a higher SCSI ID than external devices on the same
chain ... and the higher number IDs have higher priority (for 0..7). (E.g., the internal disk drive
is usually SCSI ID 6 (with the controller being 7).
For F/W SCSI, the priority order is:
7, 6, 5, 4, 3, 2, 1 , 0, 15, 14, 13, 12, 11, 10, 9, 8.
I usually recommend against putting MPEXL_SYSTEM_VOLUME_SET on an EMC, or any RAID, mostly because that usually implies that the user is over-relying on MPEXL_SYSTEM_VOLUME_SET and not utilizing
user volumes. If a system has all user data on several user volume sets, they're better
protected against the failure of a single
volume. Additionally, if a disk in MPEXL_SYSTEM_VOLUME_SET fails, there are then fewer disks requiring reload (just the ones in MPEXL_SYSTEM_VOLUME_SET).
Hence, I try to somewhat minimize the number
of disks in MPEXL_SYSTEM_VOLUME_SET.
09-11-2007 11:11 PM
EMC drives are supported on MPE/iX since OS release 5.0 so it's been a while now. The EMC Disc Array, like any other Arrays (12H, VAs, XP, NIKE), provides better disc failure protection with RAID technique than a simple JBOD / internal disc.
During server bootup, the PDC or GSP looks for the primary boot path if the primary boot is selected. With that being said, I don't believe internal disc will have priority over external disc.
Stan's statement about the SCSI addresses priority is accurate. If the EMC discs SCSI card is configured with the high SCSI addresses (6, 5, 4, etc), I don't see any reason why the EMC drives won't get serviced first.
If there are a lot of LUNs or discs configuration, and I do agree with Stan, it is always recommended to have separate user volume sets to host users datas leaving the system volume set for system, 3rd party software, spool files.
09-17-2007 06:39 AM
One of my former employers has a 989/650 running solely on an emc array. Now they are contemplating moving to an an XP array.