Hitachi AMS2100 User Manual page 35

When changing a status of a SnapShot pair, a status of a TrueCopy
pair must be Split or Failure. When changing a status of a TrueCopy
pair, a status of a SnapShot pair must be Split.
Table 1-5 shows whether a read/write to/from a SnapShot V-VOL on
the local side is possible or not in the case where a SnapShot V-VOL
and a TrueCopy P-VOL are the same LU.
•
Table 1-5: Read/Write Instructions to SnapShot V-VOL on the
TrueCopy P-VOL
–
Paired
–
Synchronizing
+, R/W
R/W
Split
+, R/W
R
+, R/W
R/W
+, R/W
Failure R
+, R/W
R/W
+ indicates a possible case, – indicates an impossible case
∆
indicates a case where a pair operation causes an error (a case that
can occur as a result of a change of the pair status to Failure)
R/W: Read/Write by a host is possible.
R: Read by a host is possible but write is impossible.
W: Write by a host is possible but read is impossible.
R/W: Read/Write by a host is impossible.
•
NOTE: Failure in this table excludes a condition in which access of an LU
is not allowed (for example, LU blockage).
SnapShot overview
Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide
Local Side (TrueCopy)
SnapShot V-VOL
Paired Synchronizing
(Restore)
–
–
+, R/W
+, R/W
+, R/W
+, R/W
+, R/W
Failure
Split Failure
(Restore)
– –
+, R
– –
+, R
∆ ∆
+, R/W , R/W , R/W
∆ ∆
+, R , R/W , R/W
∆ ∆
+, R/W , R/W , R/W
∆ ∆
+, R , R/W , R/W
∆ ∆
+, R/W , R/W , R/W
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