Hitachi Universal Storage Platform VM - Manual (Page 71)

Functional and Operational Characteristics 3-27
Hitachi Universal Storage Platform V/VM User and Reference Guide
Mode Category Function Default MCU/RCU
707 TrueCopy (open),
Universal
Replicator (open) In a cascading configuration using TrueCopy (TC) and
Universal Replicator (UR), by setting mode 707 to ON and
using the registered JNL group, the copied data from the
P-site can be stored in the journal volume in the I-site without
writing the P-site data onto the data volume in the I-site. If
P-site fails, after the R-site has taken over the production, all
the data is copied back from the R-site to the P-site.
Mode 707 = ON: The data on the P-site is not written onto the
data volume in the I-site.
Mode 707 = OFF (default): The data on the P-site is written
onto the data volume in the I-site.
Notes:
1. During the operation, this system option mode must
remain ON at the I-site.
2. Any UR pair cannot use the storage system for usual UR
operations when the system option mode is set to ON.
3. As for a TC pair combined with a UR pair in the JNLG that
is registered after the system option is set to ON, the
following operations are unavailable:
ƒ TC pair takeover, or UR pair takeover (when the P-site
is recovered, all the data in the R-site is copied onto the
data volume in the P-site).
ƒ Combination with a ShadowImage pair (I-site). The data
is not copied.
ƒ Update by a host I/O to the data volume in the I-site.
ƒ Switching to the usual cascading configuration using TC
and UR. (To switch to the usual configuration, the UR
JNLG must first be deleted.)
4. After JNLG registration, even if the mode status is switched
(ON/OFF), the status remains the same as that at the JNLG
registration.
5. If the UR pair suspends, failure suspend occurs to the
combined TC pair.
6. The TC/UR pair configuration is cascading, but the
operation differs from the cascading operation.
OFF MCU/RCU