Figure 51 Rec; Table 32 Rec Data Transfer Mode - Fujitsu ETERNUS DX500 S4/DX600 S4 Design Manual

2. Basic Functions
Backup (Advanced Copy)
Remote Copy
Remote copy is a function that copies data between different storage systems in remote locations by using the
"REC". REC is an enhancement of the EC mirror suspend method of the local copy function. Mirroring, snapshots,
and backup between multiple storage systems can be performed by using an REC.
An REC can be used to protect data against disaster by duplicating the database and backing up data to a re-
mote location.
The older models of the ETERNUS Hybrid Storage Systems and the ETERNUS Disk Storage Systems are connecta-
ble.
●
REC
REC is used to copy data among multiple devices using the EC copy method. REC is suitable for the following
usages:
• Performing system test data replication
Duplicating databases on multiple ETERNUS DX/AF storage systems
•
Backing up data to remote ETERNUS DX/AF storage systems
•

Figure 51 REC

Main site
SAN
ETERNUS DX/AF
The REC data transfer mode has two modes: the synchronous transfer mode and the asynchronous transfer
mode. These modes can be selected according to whether importance is placed upon I/O response time or com-
plete backup of the data is performed until the point when a disaster occurs.

Table 32 REC Data Transfer Mode

Data transfer mode
Synchronous transmission mode
Asynchronous transmission mode
■
Synchronous Transmission Mode
Data that is updated in a copy source is immediately copied to the copy destination. Write completion signals to
write requests for the server are only returned after both the write to the copy source and the copy to the copy
destination have been done. Synchronizing the data copy with the data that is written to the copy source guar-
antees the contents of the copy source and copy destination at the time of completion.
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
Management
server
Remote copy
Operating
volume
I/O response
Affected by transmission delay
Not affected by transmission delay
Copyright 2019 FUJITSU LIMITED
(REC)
WAN
Backup
volume
Updated log status in the case of disaster
Data is completely backed up until the point when
a disaster occurs.
Data is backed up until a few seconds before a dis-
aster occurs.
93
Backup site
Management
server
SAN
ETERNUS DX/AF
P3AM-7722-25ENZ0