NonStop S-Series Planning and Configuration Guide (G06.29+)

The Planning and Configuration Process
HP NonStop S-Series Planning and Configuration Guide—523303-021
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Enclosure Interleaving for Storage Devices
Enclosure Interleaving for Storage Devices
Within a topology branch (a processor enclosure and all the I/O enclosures connected
directly to it), you can configure paths to disk, tape, and Open SCSI devices through
adapters in different enclosures. This feature is called enclosure interleaving.
Interleaving paths across multiple enclosures increases availability, because no
enclosure is a single point of failure that could prevent access to the storage device.
Limitations
For All Disk, Tape, and Open SCSI Devices
•
All paths to a device must use the same or compatible adapter types. A PMF CRU
is compatible with an IOMF CRU and vice versa, but a 6760 adapter is not
compatible with either a PMF CRU or an IOMF CRU.
•
The primary and backup processors configured for a device must be able to
access all the adapters used by all paths to the device. Use the SCF INFO
ADAPTER command to view the access list for an adapter.
•
The first device that is configured to use a particular SAC determines which two
processors share ownership of that SAC. Devices that are later configured to use
the same SAC must also be configured to use the same two processors.
If no device paths are currently configured to use a particular SAC, then the first
device that is configured to use that SAC can use any two processors on the
access list of that SAC’s adapter.
For All Internal Disk Drives
•
The primary (-P) and backup (-B) paths must be to adapters that are in the same
enclosure.
•
The mirror (-M) and mirror-backup (-MB) paths must be to adapters that are in the
same enclosure, but these adapters need not be in the same enclosure as the
adapters for the -P and -B paths.
•
Both halves of the system-load disk volume must be in processor enclosure 01.
For All Open SCSI devices
•
The two paths to an Open SCSI device must not use SACs with identical SCSI bus
addresses.
Use the SCF INFO ADAPTER, DETAIL command to view the SCSI bus addresses
of SACs.
Note. This subsection does not apply to the Fibre Channel disk drives that reside in modular
disk drive enclosures (DDEs). $SYSTEM cannot exist on these disk drives. For more
information about the DDE, refer to the Modular I/O Installation and Configuration Guide.