Stratesave 7.0 Organized Backup Program Help Files
Incremental Database Backup
Stratesave supports incremental backups (transaction log backups). These purely incremental backups contain
only the changed data since last incremental backup (or last full/differential backup, if it is first incremental
backup).
Why incremental database backups?
The standard full or differential backups are normally run only once per day, which usually is sufficient
for pure file data. For database data though, it can be important to recover to a more accurate installation
after a crash. If SQL server completes a transaction, and crashes later in the day, it may be important to recover
to a state which contains this transaction. Best is to recover to the exact state before the crash, or at least to
a state as close as possible. The same applies to Exchange server. If the Exchange server has received an email,
the sending side takes it for granted that this email will eventually be received and read. The loss of email messages,
which have been received but not yet read, and which have not been backed up, can possibly
hurt business relationships.
Since they contain only data added or updated since last
incremental backup, incremental backups are small, and can therefore be repeated very often, to keep the critical
"time window of potential data loss" very small. Incremental database backups can for example be repeated every
30 minutes, every 10 minutes, or even more often (to once per minute shortest interval).
Incremental backups contain typically 5MBytes of data for Exchange server, and 1MBytes or less for SQL server
per database, depending on how much data changed since last incremental backup. These figures can be smaller
if compressed backups are used. If for example, the Exchange server is fully backed up once per week, with
incremental backups every 5 minutes, approx. 5*12*24*7=10'000 MBytes=10GBytes space is required to store the
incremental data. This can easily be stored on a single hard drive. SQL server supports incremental and
differential backups. A useful combination there might be weekly full backups, daily differential backups,
and incremental backups every 5 minutes. In this case the incremental data must be kept for only one day,
saving disk space. Exchange server supports only differential or incremental backups, not both
in the same backup plan. This means either full Exchange backup every night, or every week but more disk
space must be reserved for the incremental backups, because they cover updates since last weekly backup.
VSS incremental backups
VSS (Volume Snapshot Service) databases can also be selected for incremental backups, but only those VSS writer which support incremental backups.
For example VSS Exchange supports incremental backups, while VSS SQL does not.
Incremental database backups and VSS full backups
Incremental SQL Server backups can be combined with VSS (Volume Snapshot Service) full backups
(MSDEWriter, SqlServerWriter).
Restore from incremental database backups
Incremental database backups are also listed in Log, and are therefore fully kept tracked of by Stratesave.
If a database is selected for restore, Stratesave automatically restores the full database data,
differential data, and all incremental backups in the right order. The database is restored to most
recent state automatically. If desired, the process can also be done "manually", and individual differential
and incremental backups can be restored to the database as desired. Optionally, the backups can
also be restored to file, for further processing with other methods or database tools.
Databases with VSS full backup and standard differential/incremental backups must
be restored in 2 runs. First restore the VSS database with option
Don't recover restored SQL databases=On. Then Restore the incremental/differential SQL databases (selectable under SQL Server),
with option Don't recover restored SQL databases=Off.
Backup storage for incremental database backups
Incremental database backups can be stored on fixed disk only. But they can be combined with differential or
full backups to tape or removable disks. All incremental database backups are stored to same directory,
until a full or differential backups with same database is done. Then the incremental database backups
are stored on next directory in rotation scheme. For incremental database backups, the rotation is done
around the basing full or differential backups.
See also: Backup of SQL Server
Backup of Exchange Server
Stratesave Help Files