HP File System Extender (FSE) manual System allocation and job priority policy, Job priorities

Note that resource allocation requests from different partitions can have different drive and priority policies, and that the same media pool cannot be assigned to several partitions. For more information on parameters for resource allocation, see ”System allocation and job priority policy” on page 142 and ”Partition allocation and job priority policy” on page 144.

Job priorities

When a new job is created, if all of the requested resources are available in the FSE implementation, Resource Manager allocates them and the job starts performing its task immediately. If some resources are not available, a resource request of the job is put into the resource allocation queue of the Resource Manager, and the job waits for availability of the resources.

In case there are too many jobs already running for the corresponding FSE partition, the newly created job is not allowed to request resources yet, but is put into the state ”pending” instead. Such pending job waits until the current job count for the FSE partition decreases below a threshold value, and can only request the resources from the Resource Manager afterwards. Pending jobs are processed in the “first come first served” order. The threshold job count is defined by the MaxNumDrives variable (specified in the FSE partition configuration file) as follows:

ThresholdJobCount = 3/2 * MaxNumDrives

IMPORTANT: The status pending is applicable only for jobs that can be run on a particular FSE partition: migration, recall, reorganization, and maintenance jobs. Administrative and backup jobs are FSE implementation-wide jobs. They are immediately started or queued in the resource allocation queue, no matter how many jobs are already running in the FSE implementation.

When the resource request of a job is put into the resource allocation queue, the job is assigned an initial priority. When a new job is put into the queue, the priorities of all existing resource requests are recalculated; the priority of each job is then modified according to the elapsed time and the phase of the job. The resource request is then processed according to its job priority. Each time a resource is freed, the queue is checked again to allocate the free resource.

IMPORTANT: Only jobs with the status waiting for resources have priorities assigned.

For details on priority calculation, see ”Priority calculation” on page 146.

System allocation and job priority policy

The system allocation and job priority parameters are read by the Resource Manager upon its startup.

System allocation and job priority policy parameters

The configuration parameters for the system along with their definition and impact are listed below.

Maximum number of drives for migration (SystemMaxNumDrivesMigration)

Definition	Maximum number of drives that can be used for migration by all FSE partitions.
Impact	The purpose of this parameter is to prevent migration jobs from using all the drives in the
	FSE implementation. By limiting drives for migration, you ensure that drives remain
	available for other jobs (recall, administrative, recovery…). You should carefully balance
	resources according to your environment.

142 Migration, release, recall, and deletion