PowerScale OneFS Web Administration Guide

Job operation

OneFS includes system maintenance jobs that run to ensure that your PowerScale cluster performs at peak health.

The Job Engine runs system maintenance jobs in the background and prevents jobs within the same classification (exclusion set) from running simultaneously. Two exclusion sets are enforced: restripe and mark.

Restripe job types are:

• AutoBalance
• AutoBalanceLin
• FlexProtect
• FlexProtectLin
• MediaScan
• MultiScan
• SetProtectPlus
• SmartPools

Mark job types are:

• Collect
• IntegrityScan
• MultiScan

MultiScan is a member of both the restripe and mark exclusion sets. You cannot change the exclusion set parameter for a job type.

The Job Engine is sensitive to job priority. It is recommended that you have no more than three jobs of any priority running simultaneously. Job priority is denoted as 1 through 10, with 1 being the highest and 10 being the lowest. The system uses job priority when there is a conflict among running or queued jobs. For example, suppose that you manually start a job that has a higher priority than three other jobs that are already running. Job Engine pauses the lowest-priority active job, runs the new job, then restarts the older job at the point at which it was paused. Or, suppose that you start a job within the restripe exclusion set, and another restripe job is already running. The system uses priority to determine which job should run (or remain running) and which job should be paused (or remain paused).

Other job parameters determine whether jobs are enabled, their performance impact, and schedule. As system administrator, you can accept the job defaults or adjust these parameters (except for exclusion set) based on your requirements.

When a job starts, the Job Engine distributes its tasks across the nodes of your cluster. At any given time, one task belongs to one node. Multiple nodes do not share the work of one task. One node acts as job coordinator. The job coordinator tracks the tasks in progress. It works with the other nodes to load-balance the work according to the impact of the current job as determined by its policy: requested or configured. This distribution ensures that the tasks run in parallel and the load is distributed throughout the cluster.

A task is complete when there are no more items to perform for that task. Each node reports its task status to the job engine coordinator after the task is complete. The job engine coordinator merges the task results into the job results, updates the progress of the job, and stops tracking this task. When there are no more tasks to track, the phase is complete.

Checkpoints are taken periodically: when a job sends results or when the job is paused. The default checkpoint interval is 30 seconds. Some jobs request checkpoints at points of significant progress as well. If there is a power outage or if a job is paused, the job can be restarted from the point at which it was interrupted. This is important because some jobs can take hours or even days to run and can use considerable system resources.