The EC(Equivalent Copy)/REC(Remote Equivalent Copy) function of ETERNUS disk storage systems is used to copy data from a transaction volume to an unused backup volume.
To perform synchronized high-speed backup, take the following steps:
Execute swststartsync (Backup synchronous processing start command) ((1) in the following figure), the transaction volume and an unused backup volume with the same capacity are selected from the unused backup volume management area and synchronized backup processing is started.
The transaction and backup volumes reach an equivalent state. From this point on, equivalence between the transaction volume and backup volume is maintained. This status is referred to as equivalency maintenance status ((3) in the following figure).
Execute swstbackup (Backup execution command) ((4) in the figure below). The backup synchronization processing stops and the backup history information is set.
When the generation number of the newly backed up data exceeds the number of generations of backup history being kept, the oldest backup volume is treated as an unused backup volume.
Note
swstbackup (Backup execution command) cannot be executed before the transaction and backup volumes have become equivalent.
Figure 4.3 Backup using the synchronized high-speed backup function
During synchronous high-speed backup using the Suspend/Resume function, the equivalency maintenance status of EC can be set to Suspend or Resume. The synchronous backup process is therefore faster because the function can create a differential copy from the Suspend state.
For information on the Suspend/Resume function, see Chapter 5 Backup Process That Uses the Suspend/Resume Function.
Note
If all generations of backup volumes are being managed, and if no backup volume can be obtained from the unused region in the backup volume management area, backup copies cannot be created.
