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Technical white paper | HP StoreVirtual 4000 Storage
To understand network usage, you can use the Centralized Management Console to understand snapshot sizing and
replication time. For example:
• Set up local snapshot schedule and frequency; let this run for a couple of days to gather snapshot change rate
information and transfer times; this information can be reviewed using the remote snapshot tab and remote snapshot
details window
• Use information collected to characterize the amount of change on the primary volume for a given period of time
You can calculate Remote Copy transfer rate and times using information gathered using the remote snapshot tab and
details window. The remote snapshot tab provides snapshot statistics such as:
• Percent complete—the incremental progress of the Remote Copy operation
• Elapsed time—the incremental time taken by the copy operation
• Data copied—the incremental quantity of data copied
• Current rate—the rate at which data is being copied or when the remote snapshot is complete
• Average rate for the total operation
• State—the status of the operation
The snapshot details window includes the information above plus:
• Start time
• Estimated time remaining
• Completion time
• Data remaining to be copied
Using the start time, completion time, amount of data copied statistic along with Remote Copy frequency are key factors
in validating network bandwidth requirement for inter-site links.
Calculate bandwidth usage
Network bandwidth is commonly measured in megabits per second whereas storage transfer is measured in megabytes
per second. To understand the network transfer rate for remote replication sessions, convert megabytes to megabits to
determine transfer time in hours. Steps are outlined below:
Steps are outlined below:
1. Convert the size of the volume to bytes: Begin by multiplying the gigabytes by 1,024 to get megabytes.
2. Multiply megabytes by 1,024 to get to kilobytes.
3. Multiply kilobytes by 1,024 to get bytes.
4. Multiply bytes by 8 to yield the number of bits.
5. Divide the number of bits by 1,000 to yield kilobits or again by 1,000 to yield megabits.
6. Divide results by the link speed to get the number of seconds to complete the copy. Convert to the correct order of
magnitude, Kb or Mb, before dividing by the corresponding units per second of link speed.
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