PowerScale OneFS 9.5.0.0 Web Administration Guide

Source cluster snapshots

SyncIQ generates snapshots on the source cluster to ensure that a consistent point-in-time image is replicated and that unaltered data is not sent to the target cluster.

Before running a replication job, SyncIQ creates a snapshot of the source directory. SyncIQ then replicates data according to the snapshot rather than the current state of the cluster, allowing users to modify source directory files while ensuring that an exact point-in-time image of the source directory is replicated.

For example, if a replication job of /ifs/data/dir/ starts at 1:00 PM and finishes at 1:20 PM, and /ifs/data/dir/file is modified at 1:10 PM, the modifications are not reflected on the target cluster, even if /ifs/data/dir/file is not replicated until 1:15 PM.

You can replicate data according to a snapshot generated with the SnapshotIQ software module. If you replicate data according to a SnapshotIQ snapshot, SyncIQ does not generate another snapshot of the source directory. This method can be useful if you want to replicate identical copies of data to multiple PowerScale clusters.

SyncIQ generates source snapshots to ensure that replication jobs do not transfer unmodified data. When a job is created for a replication policy, SyncIQ checks whether it is the first job created for the policy. If it is not the first job created for the policy, SyncIQ compares the snapshot generated for the earlier job with the snapshot generated for the new job.

SyncIQ replicates only data that has changed since the last time a snapshot was generated for the replication policy. When a replication job is completed, SyncIQ deletes the previous source-cluster snapshot and retains the most recent snapshot until the next job is run.