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Moving devices across clusters
Depending on the metro node environment, some devices cannot be moved across clusters. The Create Device Mobility Jobs
wizard automatically filters out those devices that cannot be moved. If your device is not shown in the Available Devices list, it
could be for one of these reasons:
● The device has exported virtual volumes. Unexport the virtual volume to move this device.
● The device has virtual volumes that belong to a consistency group. Remove the virtual volume from its consistency group to
move this device.
See the Administration Guide for more information.
Mobility job transfer size
The transfer size determines the maximum number of bytes of data transferred at a time from the source to the target. When
creating a mobility job, you can control this transfer size. The greater the size, the greater the impact on host I/O. A smaller
transfer size results in the mobility job taking longer time to complete, but has a lower impact on host I/O. Monitor the mobility
job's progress and its effect on host I/O. If the job is progressing too slowly, or I/O is greatly impacted, adjust the transfer size
accordingly.
You can change the transfer size of a job while the job is in the queue or in progress. The change takes effect immediately. By
default, the GUI transfer size is the lowest, which translates to 128 KB. This transfer size provides the best throughput while
maintaining the best front-end performance in most environments.
The following table shows the different transfer-size for the mobility:
transfer-size
128 KB
2 MB
8 MB
16 MB
32 MB (ASAP)
Creating a mobility job
About this task
Creating a mobility job begins the process of moving data from one extent or device to another extent or device in the same
cluster, or from one device to another device in another cluster. The procedure for moving extents and devices is the same—
you need only to launch the appropriate wizard. Although you can create and start multiple mobility jobs, only the first 25 jobs
run concurrently. The system allocates resources and queues the remaining jobs.
CAUTION:
If there is I/O to the devices being migrated, and latency to the target cluster is equal to or greater
than 5 ms, significant performance degradation may occur.
Steps
1. From the GUI main menu, click Mobility:
● To move data from one extent to another extent within the cluster, select Move Data Within Cluster from Mobility
drop-down, and then select Extent Mobility Jobs from the CREATE drop-down.
● To move data from one device to another device within the cluster, select Move Data Within Cluster from Mobility
drop-down, and then select Device Mobility Jobs from the CREATE drop-down.
● To move data from one device to another device across clusters, select Move Data Across Clusters from Mobility
drop-down, and then select Device Mobility Jobs rom the CREATE drop-down.
2. Follow the instructions on the wizard. For additional help using the wizard, click Help.
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Moving data