5 autonegotiation, 6 remote copy mode, Autonegotiation – HP 3PAR Remote Copy Software User Manual
Page 123: Remote copy mode, Asynchronous periodic, 1 asynchronous periodic
5.3
Performance Notes for RCIP Configuration
InForm OS Version 2.3.1
Remote Copy User’s Guide
Because the MTU needs to be supported by all the switches and routers in the IP network, the
default MTU of the GigE interfaces is 1500 bytes, which is supported by all vendor hardware. If
your network supports 9000 byte MTU, it is recommended that you set the 3PAR GigE adapter’s
on page 3.11 for detailed instructions on
increasing MTU, verifying that the increased MTU size is supported by the network, and
comparing the throughput of 1500 byte and 9000 byte MTU settings.
5.1.5 Autonegotiation
The InServ Storage Server uses autonegotiation for the GigE interfaces as a default. There are
cases where autonegotiation does not work correctly and the storage server GigE port and the
local switch port use different duplex or speed configurations. This causes a significant impact
to performance and can prevent the Remote Copy links from coming up. To correct an
autonegotiation problem, you can force the duplex and speed settings of both the local and
InServ Storage Server GigE ports. The InServ Storage Server port is set using the InForm CLI
controlport
command. See
on page B.9 or the InForm OS Command Line
Interface Reference for details on using this command. Refer to your switch manufacturer’s
documentation to identify how to change the switch port settings.
The preferred option is to set both the local switch port and the storage server GigE ports to
full duplex and to specify the maximum supported speed of your network (such as 1000 Mbps).
If you are using unmanaged switches or are otherwise unable to change the local switch port
settings, then setting the storage server GigE ports to match the local switch port settings
should resolve any auto negotiation issues.
5.1.6 Remote Copy Mode
The Remote Copy mode (synchronous or asynchronous periodic) also impacts performance. For
a detailed description of synchronous and asynchronous periodic modes, see
5.1.6.1 Asynchronous Periodic
Under normal operation, snapshots are created in asynchronous periodic mode. The presence
of snapshots might decrease write performance due to the copying of the old data to the
snapshot space.