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When this option is set to
Enable
, snapshots of all volumes being backed up will be created
simultaneously. Use this option to create a time-consistent backup of data spanned across multiple
volumes, for instance for an Oracle database.
When this option is set to
Disable
, the volumes' snapshots will be taken one after the other. As a
result, if the data spans across several volumes, the resulting backup may be not consistent.
3.4.1.7
Volume Shadow Copy Service
This option is effective only for Windows operating systems.
The option defines whether a Volume Shadow Copy Service (VSS) provider—either Acronis VSS or
Microsoft VSS—has to notify VSS-aware applications that the backup is about to start. This ensures
the consistent state of all data used by the applications, in particular, completion of all database
transactions, at the moment of taking the data snapshot by Acronis Backup & Recovery 10. Data
consistency, in turn, ensures that the application will be recovered in the correct state and become
operational immediately after recovery.
The preset is:
Create snapshots using VSS
Acronis Backup & Recovery 10 will select the VSS provider automatically based on the operating
system running on the machine and whether the machine is a member of an Active Directory
domain.
Create snapshots without using VSS
Choose this option if your database is incompatible with VSS. The data snapshot will be taken by
Acronis Backup & Recovery 10. Backup process is fastest, but data consistency of the applications
whose transactions are not completed at the time of taking a snapshot cannot be guaranteed. You
may use Pre/Post data capture commands (p. 90) to indicate which commands should be performed
before and after taking the snapshot, to ensure that the data is being backed up in a consistent state.
For instance, specify pre-data capture commands that will suspend the database and flush all caches
to ensure that all transactions are completed; and specify post-data capture commands that will
resume the database operations after the snapshot is taken.
Volume shadow copy writers
Before backing up the data of VSS-aware applications, make sure that the volume shadow copy
writers for those applications are turned on, by examining the list of writers that are present in the
operating system. To view this list, run the following command:
vssadmin list writers
Note:
In Microsoft Windows Small Business Server 2003, the writer for Microsoft Exchange Server 2003 is
turned off by default. For instructions on how to turn it on, see the corresponding Microsoft Help and Support
article http://support.microsoft.com/kb/838183/en.
3.4.1.8
Compression level
This option is effective for Windows and Linux operating systems and bootable media.
The option defines the level of compression applied to the data being backed up.
The preset is:
Normal.
The optimal data compression level depends on the type of data being backed up. For example, even
maximum compression will not significantly reduce the archive size if the archive contains essentially
