SQL Server Backup and Restore - Simple Talk

Chapter 8: Database Backup and Restore with SQL Backup Pro
As a final test, we can rerun Listing 8-21, but performing a native, non-compressed
backup, and then restoring from that. In my tests, the restore times for native compressed
and SQL Backup compressed backups were roughly comparable, with the native
compressed restores performing slightly faster. Native non-compressed restores were
somewhat slower, running in around 21 seconds in my tests.
Verifying Backups
As discussed in Chapter 2, the only truly reliable way of ensuring that your various backup
files really can be used to restore a database is to perform regular test restores. However,
there are a few other things you can do to minimize the risk that, for some reason, one of
your backups will be unusable.
SQL Backup backups, like native backups can, to some extent, be checked for validity
using both BACKUP...WITH CHECKSUM and RESTORE VERIFYONLY. If both options are
configured for the backup process (see Figure 8-5b) then SQL Backup will verify that the
backup is complete and readable and then recalculate the checksum on the data pages
contained in the backup file and compare it against the checksum values generated
during the backup. Listing 8-22 shows the script.
EXECUTE master..sqlbackup '-SQL "BACKUP DATABASE [DatabaseForSQLBackups]
TO DISK = ''D:\SQLBackups\Chapter8\DatabaseForSQLBackups_FULL.sqb''
WITH CHECKSUM, DISKRETRYINTERVAL = 30, DISKRETRYCOUNT = 10, THREADCOUNT = 2,
VERIFY"'
Listing 8-22: BACKUP…WITH CHECKSUM and RESTORE VERIFYONLY with SQL Backup.
Alternatively, we can run either of the validity checks separately. As discussed in Chapter
2, BACKUP…WITH CHECKSUM verifies only that each page of data written to the backup file
is error free in relation to how it was read from disk. It does not validate that the backup
data is valid, only that what was being written, was written correctly. It can cause a lot
of overhead and slow down backup operations significantly, so evaluate its use carefully,
based on available CPU capacity.
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