An impact policy can consist of one or many impact intervals, which are blocks of time within a given week. Each impact interval can be configured to use a single, predefined impact level that specifies the amount of cluster resources to use for a particular cluster operation. The available impact levels are: 

• Paused
• Low
• Medium
• High

This degree of granularity allows impact intervals and levels to be configured per job to ensure smooth cluster operation. The resulting impact policies dictate when a job runs and the resources that a job can consume. The following table outlines the default Job Engine impact policies:

Table 2.      OneFS Job Engine default impact policies

Note: These default impact policies cannot be modified or deleted. 

You can create additional impact policies as well, either through Add an Impact Policy in the WebUI, as shown in the following figure, or by cloning a default policy and then modifying its settings as appropriate.

 Figure 4.   Job Engine impact policy management through the OneFS WebUI

A mix of jobs with different impact levels results in resource sharing. Each job cannot exceed the impact level set for it, and the aggregate impact level cannot exceed the highest level of the individual jobs.

For example:

Job A (HIGH), job B (LOW)

• The impact level of job A is HIGH.
• The impact level of job B is LOW.
• The total impact level of the two jobs combined is HIGH.

Job A (MEDIUM), job B (LOW), job C (MEDIUM)

• The impact level of job A is MEDIUM.
• The impact level of job B is LOW.
• The impact level of job C is MEDIUM.
• The total impact level of the three jobs combined is MEDIUM.

Job A (LOW), job B (LOW), job C (LOW), job D (LOW)

• The impact level of job A is LOW.
• The impact level of job B is LOW.
• The impact level of job C is LOW.
• The impact level of job D is LOW.
• The job that was most recently queued/paused, or has the highest job ID value, will be paused.
• The total impact level of the three running jobs combined with one paused job is LOW.

The following table shows the default impact policy and relative priority settings for the full range of Job Engine jobs. Typically, the elevated impact jobs are also run at an increased priority. Dell Technologies recommends keeping the default impact and priority settings, where possible, unless you have a valid reason to change them.

Table 3.      OneFS default job impact policies and priorities

Most Job Engine jobs are intended to run in the background with LOW impact. Notable exceptions are the FlexProtect jobs, which by default are set at MEDIUM impact. This setting allows FlexProtect to quickly and efficiently reprotect data without critically affecting other user activities.

Note: Dell Technologies recommends keeping the default priority and impact settings for each job.