Sybase 12.4.2 - Manual (Page 408)

Backing up your database
388
Other backup options
Specifying the block
factor BLOCK FACTOR specifies the number of IQ blocks to write to the archive
device at one time. It must be greater than 0, or BACKUP returns an error
message. BLOCK FACTOR defaults to 25 on UNIX platforms. On Windows
NT, the default BLOCK FACTOR is based on the block size of your database.
For example, if the block size is 512 bytes, BLOCK FACTOR is 120 blocks. If
the block size is 32KB, BLOCK FACTOR is 1 block.
This parameter also controls the amount of memory used for buffers during the
backup, and has a direct impact on backup performance. The effects of the
block factor are a function of disk subsystem speed, tape speed, and processor
speed. Some systems have better backup performance with a smaller block
factor, while others may have better backup performance with a larger one.
Error checking CRC ON or OFF activates or deactivates 32-bit cyclical redundancy checking
on a per block basis. ( BACKUP also uses whatever error detection is available
in the hardware.) With CRC ON , the numbers computed on backup are verified
during any subsequent RESTORE operation. The default is CRC ON .
Adding comments WITH COMMENT specifies a string up to 32KB long as part of the header
information for the backup archive. If you omit this option, BACKUP enters a
NULL. You can view the comment string by executing a RESTORE
DATABASE FROM CATALOG ONLY , or by displaying the backup
log,backup.syb, that Adaptive Server IQ provides.
If you need to back up an Adaptive Server Anywhere-only database, see the
Adaptive Server Anywhere Reference Guide for additional
BACKUP options.
Waiting for Tape Devices
During backup and restore operations, if Adaptive Server IQ cannot open the
archive device (for example, when it needs the media loaded), it waits for ten
seconds and tries again. It continues these attempts indefinitely until either it is
successful or the operation is terminated with a C
TRL - C .
Backup Examples
Example 1 — Full
backup This example makes a full, attended backup of the database asiquser to two
tape devices on UNIX. Before running this backup you must position the tapes
to the start of where the backup files will be written, and connect to
asiquser .
Then issue the following command:
BACKUP DATABASE