HP XP Continuous Access Software - Manual (Page 22)

22 HP StorageWorks Disk Array XP RAID Manager: User’s Guide
The relationship between a P-VOL and an S-VOL is called a pair.
You can use RM’s paircreate command to establish pairs. Once a pair is
established, updates to the P-VOL are automatically and continuously
copied to the S-VOL.
There are other commands to manage pairs. You can temporarily suspend
copy operations, create a SnapShot pair, resync the pair, and delete the pair
relationship.
In addition, RM has many commands to display status, manage failover,
manage failback, and set the conditions under which BC and CA execute.
Creating SnapShot pairs
-When a command is given that will generate a pair-volume, such as
paircreate, its type (SnapShot or BC) is determined by the attributes of the
S-VOL. If either of the following requirements are met, a SnapShot pair is
created:
• If the S-VOL is specified as OPEN-0V (creates an unmapped
V-VOL).
• If no S-VOL is specified.
V-VOL characteristics.
• Identified as OPEN-0V after a SCSI Inquiry or RAID Manager
command.
• An unmapped V-VOL will reply to a SCSI Inquiry but does not have
read/write ability. It will provide read capacity only. However, after a
V-VOL is mapped as the S-VOL, read/write ability is enabled.