User's Manual

23 Database Backup 89
7signal Ltd, Panuntie 6, FI-00620 HELSINKI, FINLAND, [phone], [e-mail], www.7signal.com
7signal Sapphire Carat Carat User Guide Release 3.1
The automated reporting lessens the impact of possible data loss if used in detail
and frequently. However, possibility to measurement drill-in analysis is lost as
well as any change in the network topology and other management information.
The infinite archival logging is provided in order to support online backups (see below) but it
should also be seen as a method to make system run longer automatically without user
interruption. However, the system has to be maintained and administered. It is outside of the
scope of this document to fit 7signal Sapphire to IT processes of all organizations but offline
backups with planned system halts are highly recommended.
23.3 Backup method options
23.3.1 Default state (not recommemded)
Essentially the 7signal Sapphire system default state is not a backup system at all but it is
based on the underlying database management system's robustness, fault tolerance and basic
level recovery options. In case of a permanent disk failure the data is lost. By installing the
databases on RAID disks lessens the risk further.
On default state the 7signal Sapphire relies on the database management system (IBM DB2)
logging. The assumptions are that the management information (Eye, access point and target
network) changes are not continuous but rather sporadic. The measurements are continuous
but losing few of the most recent samples is a risk that can be tolerated. Typical starting point
for analysis is one week of measurements and in case of sudden system down one would lose
the data until the system is fixed. And in case of system down it is expected that all the efforts
shall be there to bring 7signal Sapphire and other systems online again. There shall be no
special snapshots where to start operations again. It is possible to resume a state before the
interrupt, possibly the system is operational with no special effort at all.
Offline backups are possible but require user actions both to shutdown 7signal Sapphire and
do the actual backup.
Handicaps of the default method:
- no precise and secure backup (system state) to return to by default
- backup process is completely manual
- backup process requires downtime
Method strengths:
- least planning
- least resource consuming
23.3.2 First degree of backup: offline backup
Most importantly this method gives fully recoverable snapshots at the desired intervals. The
disk space requirement is an issue but not extremely serious as the frequency is totally user-
managed and the file size growth is easy to check (with the tools provided by the operating
system, not by 7signal). The downside is the downtime as the 7signal Sapphire must be halted
for the time of the backup, hence it is called offline backup. Typically this would be rather
minutes than tens of minutes. Naturally all the measurements are stopped for that time.