HP XP P9500 Storage - Manual (Page 32)

CTG 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 CTG 127, and both volumes are paired
bi-directionally, all of the target pair volumes are registered in CTG No.127 when takeover
takes place.
•
The maximum number of pairs in CTG 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 CTG 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).
CTG 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 CTG 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 CTG127.
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.
32 Planning for Continuous Access Synchronous