IBM Storwize V5010 User Manual

590 Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.1
The svctask mkfcpartnership command
Use the mkfcpartnership command to establish a one-way MM/GM partnership between the
local system and a remote system. Alternatively, use mkippartnership to create IP-based
partnership.
To establish a fully functional MM/GM partnership, you must issue this command on both
systems. This step is a prerequisite for creating MM/GM relationships between volumes on
the IBM Spectrum Virtualize systems.
When the partnership is created, you can specify the bandwidth to be used by the
background copy process between the local and remote system. If it is not specified, the
bandwidth defaults to 50 MBps. The bandwidth must be set to a value that is less than or
equal to the bandwidth that can be sustained by the intercluster link.
Background copy bandwidth effect on foreground I/O latency
The background copy bandwidth determines the rate at which the background copy is
attempted for MM/GM. The background copy bandwidth can affect foreground I/O latency in
one of the following ways:
򐂰 The following result can occur if the background copy bandwidth is set too high compared
to the MM/GM intercluster link capacity:
– The background copy I/Os can back up on the MM/GM intercluster link.
– There is a delay in the synchronous auxiliary writes of foreground I/Os.
– The foreground I/O latency increases as perceived by applications.
򐂰 If the background copy bandwidth is set too high for the storage at the primary site,
background copy read I/Os overload the primary storage and delay foreground I/Os.
򐂰 If the background copy bandwidth is set too high for the storage at the secondary site,
background copy writes at the secondary site overload the auxiliary storage and again
delay the synchronous secondary writes of foreground I/Os.
To set the background copy bandwidth optimally, ensure that you consider all three resources:
primary storage, intercluster link bandwidth, and auxiliary storage. Provision the most
restrictive of these three resources between the background copy bandwidth and the peak
foreground I/O workload.
Perform this provisioning by calculation or by determining experimentally how much
background copy can be allowed before the foreground I/O latency becomes unacceptable.
Then, reduce the background copy to accommodate peaks in workload.
The chpartnership command
To change the bandwidth that is available for background copy in the system partnership, use
the chpartnership -backgroundcopyrate <percentage_of_link_bandwidth> command to
specify the percentage of whole link capacity to be used by background copy process.
10.9.5 Creating a Metro Mirror/Global Mirror consistency group
Use the mkrcconsistgrp command to create an empty MM/GM Consistency Group.
The MM/GM consistency group name must be unique across all consistency groups that are
known to the systems owning this consistency group. If the consistency group involves two
systems, the systems must be in communication throughout the creation process.

IBM Storwize V5010 Specifications

General

Brand	IBM
Model	Storwize V5010
Category	Storage
Language	English