Air Cleaner User Manual

This field determines the maximum number of sync errors that can occur
before the reading fails. The value of this field can be any number up to
32768. Using a value of zero (0) indicates that the reading should abort
after the first sync error.
Maximum number of retries on read errors
Default=2000. When a read error occurs, by default SysBack attempts to
reread the same buffer of data up to the number of times specified by this
field. The reading fails when a read error occurs and has been retried the
number of times indicated. You can enter a number up to 32768. An entry
of zero (0) indicates that no retries should be attempted.
Note: Most tape devices, including 8MM tape drives, return an error very
quickly when a read error occurs and allows retries to be attempted
from the same data location. Others, such as DDS 4MM tape drives,
take up to 2 minutes to return from a read error. These tape devices
also do not allow read retries, but still take two minutes to return
from an attempt. Therefore, for these, and similar devices, set this
value to zero (0), because retries are not supported and any attempts
appear to pause the reading indefinitely.
Pad missing data with NULLs after sync errors?
Default=yes. When a data sync error occurs, assuming the reading is set up
to continue, the missing data is padded with NULL bytes by default. This
is to ensure that, although the data has been altered, it remains in the
correct alignment.
Note: It is very important for the data to remain in the correct alignment
when restoring raw logical volume backups. If you do not pad sync
errors with NULL bytes, all of the data following the error is
restored to a different location than expected. Volume group,
filesystem, and file/directory backups use an underlying restore
command that is capable of resynchronizing when there is missing
data in the data stream. Therefore, the value of this field is less
relevant when restoring from these backup types. However, the
restore command sometimes fails when it encounters a large stream
of NULL bytes. In this case, change this value to “no.”
SysBack Network Settings
By tuning certain network parameters, you can increase the performance of
SysBack backups and restores. You can set certain values that affect network
performance during SysBack backups and restores without affecting network
performance of other processes using the same network.
Note: Do not change the network settings using this option unless you are familiar
with network tuning. Also, you must apply the same settings to both the
SysBack server and client hosts.
In most situations, the default settings are adequate. The settings appropriate for
achieving the greatest performance on different systems and networks vary widely,
so no specific guidance can be given here. Refer to Appendix E,
“Device/System-Specific Information”, on page E-1 for any specific
recommendations.
The following fields are displayed in the SysBack Network Settings section:
16-26 IBM Tivoli Storage Manager for System Backup and Recovery: Installation and User’s Guide