HP XP P9500 Storage - Manual (Page 9)

Initial and update copy operations
Creating a pair causes the storage system to create an initial copy. The storage system
asynchronously copies updates received by the P-VOL to the S-VOL.
Initial copy
Creating a pair causes the storage system to start the initial copy and copies all the data in the
P-VOL to the S-VOL. Before the pair is created, the pair’s status is SMPL. While the initial copy is
in progress, the status is PENDING. When the initial copy is complete, the volumes are paired
(DUPLEX status).
An P-VOL continues receiving updates from the host during the initial copy. When the initial copy
is completed, update copy operations start.
Update copy
I/O sent to the P-VOL that is paired (DUPLEX status) is marked as differential data and stored in
bitmaps for transfer to the S-VOL. Update copy operations are performed periodically by the
storage system. The timing of the update copy operation is based on the amount of differential
data that accumulates and the elapsed time since the previous update.
Initial and update copy operations 9