Create and initializing load-sharing mirror relationships

Contributors

You should create a load-sharing mirror (LSM) for each root volume in the cluster. You can create the LSM on any node other than the one containing the root volume, such as the partner node in an HA pair, or in a different HA pair. For a two-node cluster, you should create the LSM on the partner of the node with the root volume.

About this task

If you create an LSM on the same node, and you then lose a disk in an HA pair, you have a single point of failure, and you do not have a second copy from which to recover your data. But when you create the LSM on a node other than the one containing the root volume, or on a different HA pair, your data is still accessible in the event of an outage.

For example, in a four-node cluster with a root volume on three nodes:

  • For the root volume on HA 1 node 1, create the LSM on HA 2 node 1 or HA 2 node 2.

  • For the root volume on HA 1 node 2, create the LSM on HA 2 node 1 or HA 2 node 2.

  • For the root volume on HA 2 node 1, create the LSM on HA 1 node 1 or HA 1 node 2.

Steps
  1. Create a destination volume for the LSM:

    volume create -vserver SVM -volume volume -aggregate aggregate -type DP -size size

    The destination volume should be the same or greater in size than the root volume.

    It is a best practice to name the root and destination volume with suffixes, such as _root and _m1.

    For complete command syntax, see the man page.

    The following example creates a load-sharing mirror volume for the root volume svm1_root in cluster_src:

    cluster_src:> volume create -vserver svm1 -volume svm1_m1 -aggregate aggr_1 -size 1gb -state online -type DP
  2. Create a replication job schedule, as described in Creating a replication job schedule.

  3. Create a load-sharing mirror relationship between the SVM root volume and the destination volume for the LSM:

    snapmirror create -source-path SVM:volume|cluster://SVM/volume -destination-path SVM:volume|cluster://SVM/volume -type LS -schedule schedule

    For complete command syntax, see the man page.

    The following example creates a load-sharing mirror relationship between the root volume svm1_root and the load-sharing mirror volume svm1_m1:

    cluster_src::> snapmirror create -source-path svm1:svm1_root -destination-path svm1:svm1_m1 -type LS -schedule hourly

    The type attribute of the load-sharing mirror changes from DP to LS.

  4. Initialize the load-sharing mirror:

    snapmirror initialize-ls-set -source-path SVM:volume|cluster://SVM/volume

    Initialization can be time-consuming. You might want to run the baseline transfer in off-peak hours.

    For complete command syntax, see the man page.

    The following example initializes the load-sharing mirror for the root volume svm1_root:

    cluster_src::> snapmirror initialize-ls-set -source-path svm1:svm1_root