To RESTORE files from multiple devices, use the RESTORESET
parameter in the RESTORE command to reference the multiple devices.
Use of the RESTORESET parameter is explained in the following pages.
You can use sequential device configuration when you have a large set of files
to RESTORE from a number of tapes and you want to speed up the
process. The sequential device configuration is described under "Using Tape
Devices Sequentially," in Chapter 3, "Preparing Storage Devices."
To RESTORE files from sequential devices:
Mount the tapes on all of the devices you plan to use.
Use the FILE command to give each device a filename that
indicates its position.
Use the RESTORESET parameter in a RESTORE
command to reference the multiple devices.
For example, to RESTORE files from three sequential devices, use the
following set of commands:
NOTE: Do not back reference the filename of a tape device immediately
before the name(s) of the file(s) you are restoring when using the
RESTORESET parameter. Instead use a placeholder for the missing
parameter normally supplied when using a single tape device. The placeholder is
provided by the use of the first semicolon (;) in the RESTORE
command.
The above RESTORE command restores all system and user files from
three sequential devices. The parentheses surrounding back-referenced
filenames group the devices into a device pool.
When RESTORE has transferred all the files from the first tape on the
first tape device, it immediately begins restoring files from the second tape
on the second tape device. While RESTORE continues, you can unload the
first tape and mount a new tape on the drive. When RESTORE finishes
restoring the files on the last device, it reverts to restoring files from the
first device. The process continues to cycle through the devices in the device
pool until it has restored all the files you specified.
If you gave the tape devices a single filename such as:
:FILE T;DEV=TAPE
Enter the following RESTORE command to RESTORE files from a
set of three sequential tape devices:
:RESTORE ;@.@.@;RESTORESET=(*T,*T,*T)
You can RESTORE files that were created using parallel devices
or parallel device pools in a sequential configuration. For example,
to RESTORE a set of reels that have been created using parallel
device pools, you must use the following logical order to mount
the reels on sequential devices: A1, A2....B1, B2 and so on. (The
first alphabetic character, in capital letters, indicates an original,
unique parallel set; the second numeric character indicates an original
sequential reel within the set.) That is, mount A1 first, followed
by A2. The reel that you mount prior to B1 should be the last "A" reel.
NOTE: Sequential RESTORE is not available for labeled tapes.
A parallel device or parallel device pool configuration can be used for
restoring files. Therefore, you can use the same designations with the
RESTORESET parameter that you can use with the STORESET
parameter. Refer to Chapter 3, "Preparing Storage Devices," for information on
storing to multiple devices.
If you gave the tape devices a single filename such as:
:FILE T;DEV=TAPE
Enter the following RESTORE command to copy files from a set of two
parallel tape devices:
:RESTORE;@.@.@;RESTORESET=(*T),(*T)
Describe parallel devices in the RESTORESET parameter by enclosing
each back-referenced device filename within parentheses. Use commas to separate
devices.
To RESTORE files from parallel device pools, use parentheses
to group the devices into pools. Separate the devices in the pool
from one another with commas. Commas also separate each device pool.
For example, the following commands copy files from two parallel
device pools. Each device pool contains two sequential devices.
In the following example, RESTORE uses a total of four devices
divided into two device pools.
If you gave the tape devices a single filename such as:
:FILE T;DEV=TAPE
Enter the following RESTORE command to copy files from a set of
parallel device pools:
:RESTORE ;@.@.@;RESTORESET=(*T,*T),(*T,*T)
NOTE: Parallel RESTOREs can be performed only with tape sets that were
created with a parallel STORE parameter. A sequential RESTORE
can be used with any tape set.
Parallel RESTORE allocates every subset of the tape set (for example,
STORESET=(*T1),(*T2) creates two subsets) to distinct parallel devices
or device pools, and expects a volume belonging to the subset to be mounted on
its allocated device or device pool only.
When DIRECTORY option is used with RESTORESET, please restore the directories
first if they are not already on the system with "RESTORE ;;DIRECTORY" command
before restoring the files with the RESTORESET option.