HP XP Racks - Manual (Page 8)

In cascaded pairs, the P-VOL for an L1 pair is a root volume and the S-VOL is a node volume. The
P-VOL for an L2 pair is the S-VOL of an L1 pair, a node volume, and the S-VOL is a leaf volume.
Initial and update copy operations
Creating a pair initiates XP7 to start the initial copy. During the initial copy, the P-VOL remains
available for read/write and can receive updates from the host. After the initial copy, XP7 performs
an update copy to periodically copy the differential data in the P-VOL to the S-VOL. Subsequent
write operations to the P-VOL are regularly duplicated to the S-VOL. The data in the P-VOL is copied
to the S-VOL.
Initial copy workflow
Initial copy is an operation that is performed by XP7 when you create a copy pair. Data on the
P-VOL is copied to the S-VOL.
XP7 goes through the following workflow to create an initial copy:
1. The volumes are unpaired. You create the copy pair.
NOTE: XP7 accepts read/write for unpaired volumes.
2. The initial copy is in progress (“COPY(PD)/COPY” status). XP7 copies the P-VOL data to the
S-VOL.
3. The initial copy is complete and the volumes are paired (“PAIR” status).
8 Business Copy overview