The total time required to copy data (steps 2 to 7 in Performing data copy) can be estimated by the following formula. The processing time depends on the number and capacity of the Azure managed disks to be migrated. If an Azure managed disk includes unused areas, the data copy processing time is shortened because unused areas are not written to the migration destination volume.
5 [min] + (Number of applicable virtual volumes × 1 [min]) + Processing time for copy I/O [s] (1) / 60
If data is migrated from one Azure managed disk, you can calculate the processing time for copy I/O (1) by using the following formula:
Capacity of the Azure managed disk to be migrated [MiB] / (Read throughput of the virtual volume [MiB/s] + Write throughput of the migration destination volume [MiB/s]) (2)
The approximate estimated time (2) is 25.6 [MiB/s].
The preceding approximate estimated time assumes that Duplication Mirroring configuration is used and the data reduction function of the migration destination volume is enabled. The estimated time might increase or decrease depending on the configuration in use or whether the data reduction function is enabled. Also, the following conditions might affect the estimated time.
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I/O load
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IOPS and setting value of throughput for the migration source Azure managed disk
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IOPS and setting value of throughput for the drive
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Number of drives on a storage node
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Number of storage nodes
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How the free capacity differs among storage controllers
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When the fault domain to which an initiator node belongs differs from the migration-destination fault domain
You can calculate the actual time by using performance information of the virtual volume and migration source volume after starting data copy (step 2 in Performing data copy) and before resuming operations on the migration destination server (step 6 in Performing data copy).
For details about how to check performance information about individual volumes, see Obtaining performance information about individual volumes in the VSP One SDS Block and SDS Cloud System Administration.
If data is migrated from two or more Azure managed disks, you can calculate the estimated time by using in the preceding formula the values for the Azure managed disk that has the largest capacity among those Azure managed disks. (Data migration can be parallelly performed for no more than 21 Azure managed disks.) If data is migrated from 22 or more Azure managed disks, data copy for 21 Azure managed disks starts first. When data copy for an Azure managed disk finishes, data copy for one of the remaining Azure managed disks starts. In the same way, data copy for the remaining Azure managed disks is performed one by one.