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exceeded when the Thin Image pair is in "PSUS" status, the pair status
changes to "PFUS."
4.
If you only want to delete snapshot data but do not want to release the
Thin Image pair, you delete the snapshot data for the pair in "PSUS" or
"PFUS" status.
5.
If you restore a Thin Image pair in "PSUS" status, snapshot data is
overwritten to the primary volume. The pair status is "COPY(RS-R) or
RCPY" when the restore process is in progress. The pair status is "PAIR"
after the restore process finishes.
6.
The pool can only contain data of predetermined capacity. If the total
capacity of snapshot data in the pool exceeds the pool capacity, the
status of the Thin Image pair becomes "PSUE." In addition, the pair
status changes to "PSUE" if a failure occurs during the restore process or
if the pool usage rate reaches 100 percent. Even if the restore process is
not in progress, the pair status may change to "PSUE" when a failure
occurs. When snapshot data is stored in the DP pool, the timing of
changing to PSUE is determined by the setting in "Suspend TI pairs when
the deletion threshold is exceeded". For details, see the
Provisioning
Guide
for your storage system.
Thin Image host access and pair status
The status of Thin Image (HTI) pairs depends on whether the hosts can read
from or write to the Thin Image pair P-VOL or S-VOLs.
The following table explains the host access and pair status for snapshot
pairs.
HTI pair status
P-VOL
S-VOL
Read
Write
Read
Write
SMPL
Yes
Yes
No
No
SMPL(PD) or SMPP
Yes
Yes
No
No
COPY
Yes
Yes
No
No
PAIR/PFUL
Yes
Yes
No
No
PSUS/PFUS
Yes
Yes
Yes
Yes
COPY(RS-R) or RCPY
Yes
Yes
No
No
PSUE
Yes
Yes
No
No
Legend
Yes: Hosts can access the volume
No: Hosts cannot access the volume
Caution:
If a host uses a software application to monitor Thin Image pair
volumes other than Thin Image, the S-VOL status determines if the software
application ends abnormally. For example, if the S-VOLs are in a status other
than "PSUS" and "PFUS," the host can reject access.
Overview of Thin Image
39
Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series