SCF Reference Manual for the Storage Subsystem (G06.28+, H06.05+, J06.03+)

For a partition capacity upgrade, you can temporarily mirror partitions of different sizes. If it is
desired to keep both mirrored disks of different sizes up, the SCF CAPACITYMISMATCH option
must be turned ON for the LDEV. Normally mirroring partitions of different sizes is used temporarily
as part of an online disk capacity upgrade operation.
To simplify disk replacement, a mirrored disk partition must be on two physical disks that are
partitioned in the same configuration. During disk replacement, the ADD PARTITION, LIKE command
can be used to configure the replacement disk to be like the mirror disk.
$SYSTEM cannot be configured (via OSM Low-Level Link) to a disk partition. Only an unpartitioned
disk pair can be used as $SYSTEM. Any other NonStop disk LDEV can be configured to a disk
partition.
Configuring Mirrored Disks
The mirroring examples in this section are based on internal SCSI disks. If you are mirroring model
45xx or M8xxx disks, you also need to specify PRIMARYDEVICEID, BACKUPDEVICEID,
MIRRORDEVICEID, and MBACKUPDEVICEID attributes.
For considerations for the type of disk you are mirroring, see “Mirrored Disk Placement” (page 77)
and “Considerations for M8xxx Fibre Channel Disks” (page 71)
Configuring Internal Mirrored Disks to Revive Automatically
The AUTOREVIVE attribute affects the start behavior of internal mirrored disks differently depending
on the object type specified:
• AUTOREVIVE for the SUBSYS object type:
-> ALTER SUBSYS $ZZSTO, AUTOREVIVE ON
If AUTOREVIVE is ON for the storage subsystem, automatic revive operations are allowed. If
AUTOREVIVE is OFF for the storage susbsytem, automatic revive operations are not allowed.
AUTOREVIVE for the SUBSYS overrides AUTOREVIVE for the PROFILE.
• AUTOREVIVE for the DISK object type:
-> ALTER DISK $DATA2, AUTOREVIVE ON
For an individual disk, this attribute controls whether a disk is automatically revived after
insertion or at system load or processor reload. AUTOREVIVE for disk only occurs if
AUTOREVIVE for SUBSYS is also turned ON
These attributes interact as follows:
DISK AUTOREVIVE OFFDISK AUTOREVIVE ON
Autorevive after:Autorevive after:SUBSYS AUTOREVIVE ON
• System load No• System load Yes
• •Disk insertion Yes Disk insertion No
Autorevive after:Autorevive after:SUBSYS AUTOREVIVE OFF
• System load No• System load No
• •Disk insertion No Disk insertion No
You might want to use this configuration scheme:
• Configure your system to have disks revive automatically (by setting AUTOREVIVE ON for the
subsystem).
• Make exceptions where you want some disks to not revive automatically (by setting those
disks to AUTOREVIVE OFF).
78 Configuring Disks