Operating System Software User Manual

To optimize throughput, consider increasing the MTU size to 9000 bytes.
“Checking RCIP Link Throughput and Latency” (page 33)1. Check link throughput. The output of the cli
checkrclink command displays the maximum MTU
for the specified RCIP links.
• If the Max MTU value is 1500 bytes, you cannot
increase MTU.
• If the Max MTU is 9000 bytes, you might be able to
increase MTU.
“Increasing MTU” (page 33)2. If the Max MTU value is 9000, verify that your setup
allows an MTU increase.
3. If supported, increase the MTU.
Limiting Throughput
“Limiting Throughput for Asynchronous Periodic Volume
Groups” (page 129)
To save on leased-line charges during synchronization,
limit throughput.
“Removing Throughput Limits” (page 130)To send as much data as possible, remove throughput
limits.
By default, HP 3PAR Remote Copy sends data as fast as it can on all links between a remote-copy
pair. However, this method can be expensive if you are resynchronizing asynchronous periodic
volume groups over a leased line that charges based on the bit rate used.
When you limit throughput, HP 3PAR Remote Copy meters the data and sends it out at a rate less
than or equal to the specified limit.
Limiting Throughput for Asynchronous Periodic Volume Groups
NOTE: Throughput limits are not recommended for volume groups in synchronous mode because
limited throughput results in higher latency for host writes to the primary volumes.
To limit throughput for asynchronous periodic volume groups, follow these steps:
1. To stop the volume groups, issue either of the following commands:
# stoprcopygroup <group_name>
or:
# stoprcopygroup -pat <pattern>
where <pattern> represents the pattern of volume group names to stop (for example,
Group*).
2. To specify the rate of data transfer, issue the following command:
# setrcopytarget tput <tput_value>{g|G|m|M|k|K} <target_name>
Limiting Throughput 129