HP XP Racks - Manual (Page 44)

Continuous Access Journal
Cnt Ac-S and Continuous Access Journal can share the same pair volumes. Using a combined Cnt
Ac-S and Continuous Access Journal configuration can extend disaster recovery options to a third
data center.
Like Cnt Ac-S, a Continuous Access Journal pair maintains a copy of the production volume in a
second location. However, unlike Cnt Ac-S, the Continuous Access Journal S-VOL is asynchronous,
and the secondary system can be located much greater distances from the local and remote Cnt
Ac-S sites.
Creating both a Cnt Ac-S and a Continuous Access Journal backup ensures that a copy in a third
location is available in the event that the local site or one of the systems fails.
Configurations consisting of Cnt Ac-S and Continuous Access Journal pair volumes are covered
extensively in the HP XP7 Continuous Access Journal User Guide.
Virtual LUN
Virtual LUN volumes can be assigned to Cnt Ac-S pairs, with the following restrictions:
•
The S-VOL must have the same capacity as the P-VOL.
•
When performing Virtual LUN operations on an existing Cnt Ac-S P-VOL or S-VOL, you must
release the pair first to return the volume to SMPL status.
For more information, see the HP XP7 Provisioning for Open Systems User Guide.
Auto LUN
The following table shows when Cnt Ac-S volumes may be used as Auto LUN volumes.
Used as Auto LUN volume? Volume/pair status
No P-VOL/S-VOL in COPY status
Yes P-VOL/S-VOL in PAIR status
Yes P-VOL/S-VOL in PSUS status
Restrictions
The following restrictions must be followed when a Cnt Ac-S volume in PAIR status is used as a
Auto LUN volume:
•
Set I/O rates less than 50 IOPS while migrating volumes; if more than 50 IOPS, volumes may
not be migrated.
•
If a data path failure occurs, remove the failure then migrate the volume.
•
If an external volume or a THP V-VOL is used, information from before the volume is migrated
displays in the secondary system Remote Web Console window. If the Auto LUN is completed
and the Cnt Ac-S pair is split and resynchronized, the volume's information is updated.
•
Do not migrate P-VOL and S-VOL at the same time, or a host I/O timeout will occur.
•
Do not change the status of a volume during migration; the status may not change.
44 Sharing Continuous Access Synchronous volumes