HP 3000 Manuals HP 3000 Manuals
Chapter 2 Backing Up Files
The TurboSTORE/XL II program allows you to store files to a single device
or to multiple devices.
The best way to use your backup devices depends upon the characteristics
of the files that you are storing, your needs for compatibility with
other versions of MPE, and your system configuration.
The characteristics of the set of files help determine choices (or
options) for storing them. Use the following guidelines to select the
most appropriate method:
* How many files do you need to back up?[REV BEG]
Generally, the more files in the file set, it is to your advantage
to use multiple devices or a high capacity storage device such as
a DASS optical disk device.
* If you are storing only a few files of moderate size, one
backup device such as a tape drive or DDS-format device is
sufficient.
* If you are storing many files (for example, all the files
in an account, or a smaller number of very large files), a
multiple-device backup or single DASS device is best.
[REV END]
* Do the backup files need to be compatible with another system?
Compatibility with other versions of MPE limits your choices. If
you need to produce STORE tapes that are compatible with MPE V/E
using the TRANSPORT parameter, you can only store files to a
single device.
* Does your system configuration include multiple backup devices?
If you are not limited by your need for compatibility with MPE V/E
or earlier versions of MPE XL, your system configuration is the
most important determining factor of which multiple-device method
to use. Use the following guidelines to select a method:
* Which and how many backup devices do you have?
If you have two or three devices, use either parallel or
sequential devices. If you have at least four devices, use
two or more parallel device pools.
* Do you intend to use labeled tapes?
Labeled tapes can be used with a single device and parallel
devices, but not with sequential devices. Unlabeled tapes
can be used with single, parallel, and sequential devices.
* Do you use the same back up procedures on a regular basis?
If you store the same information to tape regularly, you
can keep the STORE parameters and options in an indirect
file (a text file containing the file set and the
parameters for a STORE command). Instead of listing the
files to store and the options you want to use in a STORE
command, enter the STORE files in a text file and reference
the text file name in the STORE command. For example:
@.@.@;*T;DIRECTORY;ONVS=MPEXL_SYSTEM_VOLUME_SET,NV1
STORE ^BACKUP;*T
The above example references the file BACKUP as an indirect
file.
* Do you have critical applications that need to be available 24
hours a day?
If your system environment includes applications that need to be
available on a 24-hour basis, you should use TurboSTORE/XL II with
On-Line Backup. With the online backup feature, you do not need
to shut the system down to perform a backup. The only impact on
processing is a brief period of approximately five minutes of data
inaccessibility while the backup process begins.
Use online backup to store critical applications that need to be
available at all times. At the time online backup is started, all
files must be closed for approximately five minutes while they are
attached to a shadow logging subsystem. The attachment to the
logging subsystem ensures that the files are both physically and
logically consistent. Files that are open for write access at the
time online backup is initiated will not be included in the
backup. After the backup process begins, users may open their
files for read, write, and purge access.