You can configure a replication policy to run according to a schedule, so that you can control when replication is performed. You can also configure policies to replicate the data captured in snapshots of a directory. You can also configure a replication policy to start when SyncIQ detects a modification to the source directory, so that SyncIQ maintains a more current version of your data on the target cluster.
Scheduling a policy can be useful under the following conditions:
- You want to replicate data when user activity is minimal
- You can accurately predict when modifications will be made to the data
If a policy is configured to run according to a schedule, you can configure the policy not to run if no changes have been made to the contents of the source directory since the job was last run. However, if changes are made to the parent directory of the source directory or a sibling directory of the source directory, and then a snapshot of the parent directory is taken, SyncIQ will create a job for the policy, even if no changes have been made to the source directory. Also, if you monitor the cluster through the File System Analytics (FSA) feature of InsightIQ, the FSA job will create snapshots of /ifs, which will most likely cause a replication job to start whenever the FSA job is run.
Replicating data contained in snapshots of a directory can be useful under the following conditions:
- You want to replicate data according to a schedule, and you are already generating snapshots of the source directory through a snapshot schedule
- You want to maintain identical snapshots on both the source and target cluster
- You want to replicate existing snapshots to the target cluster
To do this, you must enable archival snapshots on the target cluster. This setting can only been enabled when the policy is created.
If a policy is configured to replicate snapshots, you can configure SyncIQ to replicate only snapshots that match a specified naming pattern.
Configuring a policy to start when changes are made to the source directory can be useful under the following conditions:
- You want to retain a up-to-date copy of your data at all times
- You are expecting a large number of changes at unpredictable intervals
For policies that are configured to start whenever changes are made to the source directory, SyncIQ checks the source directories every ten seconds. SyncIQ checks all files and directories underneath the source directory, regardless of whether those files or directories are excluded from replication, so SyncIQ might occasionally run a replication job unnecessarily. For example, assume that newPolicy replicates /ifs/data/media but excludes /ifs/data/media/temp. If a modification is made to /ifs/data/media/temp/file.txt, SyncIQ will run newPolicy, even though /ifs/data/media/temp/file.txt will not be replicated.
If a policy is configured to start whenever changes are made to the source directory, and a replication job fails, SyncIQ waits one minute before attempting to run the policy again. SyncIQ increases this delay exponentially for each failure up to a maximum of eight hours. You can override the delay by running the policy manually at any time. After a job for the policy completes successfully, SyncIQ will resume checking the source directory every ten seconds.
If a policy is configured to start whenever changes are made to the source directory, you can configure SyncIQ to wait a specified period of time after the source directory is modified before starting a job.