HP 3000 Manuals HP 3000 Manuals
Increasing Record Size
Files are stored with the greatest efficiency by using the maximum tape
record (buffer) size allocated to a given backup device. Performance
increases because data transmission is more efficient and the amount of
media used for interrecord gaps decreases.
The maximum tape record size of MPE XL-supported backup devices differs
from device to device and is shown in Table 3-1 below:
Table 3-1. Maximum Tape Record Sizes
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| |
| Tape Drive Record Size |
| |
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| |
| HP 7974 16 Kbytes |
| |
| HP 7976 16 Kbytes |
| |
| HP 7978A 16 Kbytes |
| |
| HP 7978B 32 Kbytes |
| |
| HP 7979 32 Kbytes |
| |
| HP 7980 32 Kbytes |
| |
| HP 7980XC 32 Kbytes |
| |
| HP 1300H 32 Kbytes |
| |
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Normally when a STORE command is issued, a default record size of 16
Kbytes is utilized. However, by using the MAXTAPEBUF parameter of the
STORE command, the maximum record size of the specified device is
automatically used. If multiple backup devices are specified using the
STORESET and MAXTAPEBUF parameters together, STORE uses the maximum
record size; the lowest common denominator of the different devices.
This ensures that the record sizes are the same on all volumes of the
tape set.
NOTE Do not use the MAXTAPEBUF parameter with a backup device of 32
Kbytes record size if you anticipate restoring the tape created to
a backup device whose maximum record size is 16 Kbytes. However,
restoring a tape to a larger maximum record size device does not
cause problems.
To increase record size when storing files, use the MAXTAPEBUF parameter
in your STORE command. For example,
FILE T;DEV=TAPE
STORE @.OPERATOR.SYS;*T;MAXTAPEBUF