Copy-On-Write Snapshot Pair Status - Hitachi VSP F1500 User And Reference Manual

A Copy-on-Write Snapshot pair is generated in the following two cases:
• When a V-VOL (OPEN-0V) is specified as an S-VOL.
• When a pool for Copy-on-Write Snapshot is specified as the pool type.
A V-VOL has the following characteristics:
• It appears as "OPEN-0V" to identify a V-VOL easily via the SCSI Inquiry or
CCI.
• A V-VOL unmapped to the S-VOL of a Copy-on-Write Snapshot will reply
to a SCSI Inquiry, but Reading and/or Writing is not allowed. LDEV will
reply the capacity setting as an LU to SCSI Read Capacity.
• A V-VOL that has become the S-VOL of a Copy-on-Write Snapshot will
reply to a SCSI Inquiry, and Reading and/or Writing is allowed.

Copy-on-Write Snapshot pair status

Each paired volume consists of a primary volume (P-VOL) and a secondary
volume (S-VOL). Each volume has the status for controlling the pair state.
The P-VOL controls the pair state that is reflected on the status of the S-VOL.
The major pair statuses are "SMPL", "PAIR", "PSUS", "COPY", and "RCPY".
The status is changed when the CCI command is issued. A read or write
request from the host is allowed or rejected according to the status.
P-VOL
Status
SMPL
PAIR
(PFUL)
COPY
RCPY
PSUS
(PFUS)
Table 6-10 Copy-on-Write Snapshot Pairing Status
Pairing Status
Unpaired (Copy-on-Write Snapshot) volume
The Copy-on-Write Snapshot available state
allocated the resource.
The preparing state allocates the resource for
the Copy-on-Write Snapshot.
The copying state from Copy-on-Write
Snapshot to the primary volume by using
restore option.
The differences of the updated data of the
primary and secondary volume are controlled
with copying on write.
Data replication operations with CCI
Command Control Interface User and Reference Guide
Primary Secondary
R/W enabled
R/W disable
R/W enabled R/W disable
R/W enabled R/W disable
R/W enabled R/W disable
R/W enabled R/W enabled
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