The conventional snapshot high-speed backups using One Point Copy (OPC) must copy the entire transaction volume to the backup volume each time a backup (OPC) is started. However, by using the QuickOPC function, there is no need to physically copy the entire transaction volume every time as long as the same transaction volume/backup volume pair is used. The QuickOPC function copies only the "differential data" (the data that has changed since the previous backup), so a complete snapshot image can be created and the time required to physically copy the data can be greatly reduced.
The snapshot high-speed backups that use the QuickOPC function are called "differential snapshot high-speed backups" in this manual.
A comparison between conventional snapshot high-speed backups and differential snapshot high-speed backups is shown below.
Note
To perform differential snapshot high-speed backups, you must use an ETERNUS storage system that supports the QuickOPC function.
The QuickOPC function can only be used for intra-cabinet copies (OPC), and cannot be used for inter-cabinet copies (ROPC).
The QuickOPC function cannot be used to back up SDX objects in units of logical volumes.
Point
Using the QuickOPC function, updates that have occurred on the copy source and copy destination are recorded by the hardware after the OPC logical copy completes. The status in which update locations are recorded by the hardware is referred to as the "tracking status".
Figure 7.1 Comparison between conventional snapshot high-speed backups and differential snapshot high-speed backups
There is no difference between conventional snapshot high-speed backups and differential snapshot high-speed backups as far as backing up data to tape is concerned. The tape backup history is created from the backup volume, which is the copy destination for the QuickOPC. As a result, there is also no difference between conventional snapshot high-speed backups and differential snapshot high-speed backups as far as restoring data from tape is concerned.
