User's Manual
93
- 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
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.
Offline backup 1st degree is available in every install and run scenario of 7signal Sapphire.
One can start offline backup with a tool or have it run by the system in a circadian manner.
Method handicaps:
- backup process requires downtime
Method strengths:
- simple to recover
- recovered system state is thoroughly consistent
TIP: offline backup is suitable for environments that
require automated backup but do not have special
backup policy hardware nor other extensive resources.
2nd degree of backup: online backup
The requirement for the online backup is that infinite archive logging is enabled.
When online backup is operational, the most significant benefit is the ability to run circadian
backups online i.e. 7signal Sapphire remains operational and continues testing while
creating the backup. As opposed to offline backup, the system is online all the time
producing measurements.
The first and the most important assumption is that there is a storage device available that
in practice is a so-called endless device. 7signal cannot and shall not guarantee any checks
on the device but it is assumed to be available all the time and have the capacity for massive
data transfers. The user is responsible for the storage capacity.
NOTE: backups are not done incrementally in any case.
This means that over time the needed to dump the
database increases but more importantly the disk space