Data Path; Consistency Groups; Interfaces - Hitachi G200 User Manual

- If setting S-VOL's write option as enable, Write access from host
application of secondary site to S-VOL become possible. If not, it will hold
the status at the time of pair split.
- When P-VOL and S-VOL is not synchronized, differential data will be
saved as bitmap until P-VOL and S-VOL resynchronizes.
- If you resync pairs, only the data which is not synchronized will be
transferred so it will save time for copying.
• When resynchronized, data changed in the P-VOL is copied to the S-VOL.
• When necessary, data in the S-VOL can be copied to the P-VOL.
During normal operations, the P-VOL remains available to the host for read
and write I/O operations. The secondary system rejects write I/Os for the S-
VOL. The S-VOL can only be written to when the pair is split and when the
write-enable option is specified for the S-VOL. In this instance, S-VOL and P-
VOL track maps keep track of differential data and are used to resynchronize
the pair.

Data path

TrueCopy operations are carried out between primary and secondary storage
systems connected by a Fibre Channel or iSCSI interface. The data path, also
referred to as the remote copy connection, connects ports on the primary
storage system to the ports on the secondary storage system.
One data path connection is required, but two or more independent
connections are recommended for hardware redundancy.

Consistency groups

A consistency group is a grouping of pairs upon which copy operations are
performed simultaneously, and in which the pairs' status remains consistent.
A consistency group can include pairs that reside in storage systems.
You can issue a TrueCopy command to the consistency group so that it is run
on all pairs in the group. The pairs' statuses change at the same time, though
this depends on the group options you have set. Some pair operations take
priority under certain circumstances. Full information is covered in
Consistency group planning on page

Interfaces

You perform TrueCopy operations using one of the following interfaces:
• Device Manager - Storage Navigator, which is a browser-based interface
from which TrueCopy is set up, operated, and monitored. The GUI
provides the simplest method for performing operations, requiring no
previous experience.
Hitachi TrueCopy® User Guide for Hitachi Virtual Storage Platform Gx00 and Fx00 Models
3-16.
TrueCopy overview
1-5