Delaying block device replication

Learn to delay block device replication by using the command-line.

Before you begin

Before you begin, make sure that you have the following prerequisites in place:

A running IBM Storage Ceph cluster.
Root-level access to the node.

About this task

Whether using one-way or two-way replication, you can configure delayed replication for RADOS Block Device (RBD) mirrored images. Delayed replication provides a buffer period, allowing you to revert unintended changes on the primary image before they are propagated to the secondary image.

Note: Delaying block device replication is only applicable with journal-based mirroring.

To implement delayed replication, the rbd-mirror daemon within the destination storage cluster should set the rbd_mirroring_replay_delay = _MINIMUM_DELAY_IN_SECONDS_ configuration option. This setting can either be applied globally within the ceph.conf file utilized by the rbd-mirror daemons, or on an individual image basis.

Procedure

Utilize delayed replication for a specific image, on the primary image by running the following rbd command.

Syntax,

rbd image-meta set POOL_NAME/IMAGE_NAME conf_rbd_mirroring_replay_delay MINIMUM_DELAY_IN_SECONDS

The following example sets a 10 minute minimum replication delay on image vm-1 in the vms pool.

[root@rbd-client ~]# rbd image-meta set vms/vm-1 conf_rbd_mirroring_replay_delay 600