NetBackup Properties
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• If a write affects data that has not been backed up yet and has not
changed since the backup started, Open Transaction Manager copies the
original data from the disk to its cache before writing the new data to the
disk. This maintains the snapshot. The size of the cache is determined by
the Initial cache size and Maximum cache size settings.
• If a write affects data that has already been backed up, Open Transaction
Manager writes the data directly on the disk without changing the cache.
The same action occurs if the write affects data that has already changed
since the start of the backup (and therefore is already in the cache).
Read requests:
• If the request is from NetBackup, the action depends on whether the data
on the disk has changed since the backup started. If the data has
changed, it is read from the cache. If the data is unchanged, it is read
directly from the disk.
• If the request is from an application other than NetBackup, the data is
read directly from disk in all instances, because the snapshot is not
required.
The following topics explain the settings on this tab.
Enable OTM during backups
Enables open transaction management.
Cache File
Specifies the location of the cache file that contains the copy of data that
changes during the backup. For best performance, place the cache file on a
drive that is not backed up. By default, the program determines the cache
location at run time (for example,
C:\temp
).
Initial Cache Size
Specifies the initial size of the cache file (in megabytes). If you do not specify a
value, NetBackup sets it to 10 megabytes. If you set the value to 0, NetBackup
sets it to 10% of the used disk space.
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
