HP XP7 Storage - Manual (Page 31)

The following table lists and describes the SOMs for Continuous Access Journal. For a complete
list of SOMs for the XP7, see the HP XP7 Owner Guide.
NOTE: The SOM information may have changed since this document was published. Contact
your HP representative for the latest SOM information.
Table 2 System option modes
Description Mode
When the SVP detects a blocked path: 448
Mode 448 ON: An error is assumed and the mirror is immediately suspended.
Mode 448 OFF: If the path does not recover within a specified period of time, an error
is assumed and the mirror is suspended.
Note: Mode 448 setting is available only when mode 449 is set to OFF.
Mode 449 ON: The SVP does not detect blocked paths. 449
Mode 449 OFF: The SVP detects blocked paths and monitors the time until the mirrors
are suspended.
It is strongly recommended that the path between the main and secondary storage
systems have a minimum data transfer speed of 100 Mbps. If the data transfer speed 466
falls to 10 Mbps or lower, Cnt Ac-J operations cannot be properly processed. As a
result, many retries occur and Cnt Ac-J pairs may be suspended. This SOM is provided
to ensure proper system operation for data transfer speeds of at least 10 Mbps.
ON: Data transfer speeds of 10 Mbps and higher are supported. The JNL read is
performed with 4-multiplexed read size of 256 KB.
OFF (default): For conventional operations. Data transfer speeds of 100 Mbps and
higher are supported. The JNL read is performed with 32-multiplexed read size of 1
MB by default.
Note: The data transfer speed can be changed using the Change JNL Group options.
With mode 474 set to ON, the initial copy time for a Cnt Ac-J pair is improved when
using the Cnt Ac-S initial copy operation. 474
The procedure requires use of a script, with the following operations:
•
Cnt Ac-J initial copy operation, with "None" specified for the Initial Copy parameter.
•
Split the Cnt Ac-J pair.
• Cnt Ac-S initial copy operation, using the split Cnt Ac-J pair volumes.
•
Delete the Cnt Ac-S pair.
• Resynchronize the Cnt Ac-J pair.
Mode 474 ON: Using RAID Manager improves performance.
Mode 474 OFF: Operations run normally.
If the P-VOL and S-VOL are both THP V-VOLs, initial copy performance might not improve
with SOM 474 set to ON. This is because with THP V-VOLs, not all areas in a volume
are allocated for Cnt Ac-J; therefore not all areas in the P-VOL are copied to the S-VOL.
With less than the full amount of data in the P-VOL being copied, the initial copy
completes in a shorter time, which may not be improved with SOM 474.
Notes:
1. Set this mode for both primary and secondary systems.
2. When this mode is set to ON:
-Execute all pair operations from RAID Manager/BCM.
-Use a dedicated script.
-Initial copy operation is prioritized over update I/O. Therefore, the processing speed
of the update I/O slows down.
-Version downgrade is disabled.
-Take Over is not available.
Guidelines for preparing systems for Cnt Ac-J 31