- To prevent all paths on the external volumes from
being blocked due to timeout on HUS or AMS 2000 series, change the following
timer values.
Timer value to be changed Recommended value I/O timeout value for the external connection port on the local storage system* 25 seconds or more
(Applicable time range: 5 to 240 seconds)
Blocked path monitoring time for the external connection port on the local storage system* 35 seconds or more
(Applicable time range: 5 to 180 seconds)
Command timeout value on the host 60 seconds or more * The timer value settings can be changed in the Edit External WWNs or Edit External iSCSI Targets window. For more information about how to change the settings, see Changing the port settings of an external storage system. - Avoid unnecessary load to the external storage system. Path mode between storage systems is Multi mode. Therefore, when many external paths and mapping volumes are mapped, the load to the external system is high, and some commands from a host to the local storage system or from the local storage system to an external system might time out. To keep the proper load, the following settings are recommended:
- Specify two external paths. Set the paths to the ports of each controller of the AMS 2000 series system.
- Set the queue to 500 or fewer commands issued at
the same time from a AMS 2000 series system. The formula to calculate
the number of queue commands per system is as follows.
number-of-queues x number-of-external-paths x number-of-concurrent-external-volume-commands < 500
For more information about command queue settings, see Changing the port settings of an external storage system.
- When using external volumes for replication, the
copy operation needs to be distributed to two or more RAID groups.
There is an upper bound to the number of pairs that can be used for initial copy or resynchronization. Therefore, the copy operation might focus on a specific RAID group according to the order of the operation when it is performed to two or more external volumes.
If the copy operation focuses on a specific RAID group, then the AMS 2000 drive could bottleneck.