HP XP Racks - Manual (Page 31)

CG 127 behavior and restrictions when a pair is suspended
Note the following behaviors and restrictions regarding the consistent suspending of all P-VOLs
when a pair suspends.
•
When a failure occurs or if a pair is suspended by RAID Manager, all P-VOLs will be
suspended.
•
When P-VOLs and S-VOLs are registered in CG 127, and both volumes are paired
bi-directionally, all of the target pair volumes are registered in CG No.127 when takeover
takes place.
•
The maximum number of pairs in CG 127 is 4,096.
•
For P-VOLs to be suspended, a failure must occur, then a write I/O operation must occur in
any of the pairs.
•
When P-VOL status is PAIR and S-VOL status is PSUE, if a write I/O is executed, all P-VOLs
registered in CG 127 are suspended by failure.
When P-VOL status is PAIR and S-VOL status is PSUE, you can restore PAIR status to the S-VOL
by suspending the P-VOL and then resynchronizing the pair. With RAID Manager, use the -l
option.
•
When the S-VOL is suspended due to an intermittent communication failure, the P-VOL might
not be suspended (P-VOL with no I/O processing stays in PAIR).
CG 127 behavior and restrictions when the data path fails
Note the following behaviors and restrictions regarding the consistent changing of all S-VOLs to
PSUE status when the secondary system is disconnected.
•
S-VOLs must be in PAIR or COPY status in order to change to PSUE status. They cannot be in
PSUS or SSUS status.
•
All connections to the primary system must be disconnected.
S-VOLs cannot be changed to PSUE status if the MinimumPath field is set to a value other than
1 on the primary system (RCU Option dialog box).
•
Changing status to PSUE may take up to 10-minutes if there are many pairs.
•
All S-VOLs will be changed to PSUE even if all data paths are recovered in the middle of the
process.
•
If the data paths are disconnected for a short time (less than one minute), S-VOLs may not
change to PSUE status because the storage system does not detect the disconnection.
•
After a power outage, all S-VOLs registered in CG 127 will be changed to PSUE status.
•
If write I/O is executed when the P-VOL is in PAIR status and the S-VOL is in PSUE status, the
secondary system does not accept updates, and the primary system suspends the P-VOL.
•
Remote I/O (RIO), which is issued during the change to PSUE status, is accepted by the
secondary system.
•
When a pair's status is changing to PSUE:
- It cannot be resynchronized.
- It cannot be created and registered in CG127.
However, a pair can be deleted when status is changing to PSUE.
•
In a bi-directional configuration, if all data paths for the primary system of the reverse direction
pair are disconnected when pair status is changing to PSUE, the disconnection may not be
detected.
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