HP File System Extender (FSE) Multiple copying, Parallel copying, Example of resource allocation

Example of resource allocation

The following is an example output of the fsejob --listcommand, which shows the resource allocation queue with job priorities. Note that jobs that are currently not waiting for resources do not have priorities assigned.

cumulus:/root # fsejob -l
JobId	Partition	Type	Prio	Started	Status
20021119000043	Part01	migration	n/a	2002/11/19 08:02:05 writing to medium
20021119000044	Part01	migration	1023	2002/11/19 08:02:40 waiting for resources
20021119000045	Part01	migration	1009	2002/11/19 08:03:15 waiting for resources
20021119000046	Part02	recall	4000	2002/11/19 08:03:38 waiting for resources
20021119000047	Part01	migration	1030	2002/11/19 08:02:40 waiting for resources
20021119000048	Part02	migration	1016	2002/11/19 08:03:15 waiting for resources
20021119000049	Part01	recall	n/a	2002/11/19 08:03:38 reading from medium
20021119000050	Part01	migration	n/a	2002/11/19 08:04:30 writing to medium

Multiple copying

FSE migrates data to FSE media to maintain an offline copy of the data on HSM file systems. Each file on an HSM file system has a corresponding copy on an FSE medium. The medium that stores such a copy belongs to the FSE media pool assigned to the respective FSE partition. Therefore all files on a particular HSM file system are migrated to the same media pool. In case of a disaster, this has the following advantages:

•A complete HSM file system can be restored from the FSE media, including the file system structure for the migrated file data.

•The HSM file system restore period is reduced since only the active (online, frequently used) file data need to be restored.

In order to enhance security and eliminate the risk of physical damage to your media, which can result in data loss, you can configure FSE to make redundant copies of the file data during migration jobs. To do this, you need to configure additional media pools, allocate additional media, and assign them to the particular HSM file system. All media pools must be configured with the same block size (BlockSize variable in the FSE media pool configuration file).

The number of FSE media pools assigned to the same FSE partition equals the number of copies the data from that FSE partition will have on FSE media. If you have more copies of file data on FSE media, you are able to recall your data from any available copy, thus benefiting on recall speed and data safety.

Depending on the configuration of your FSE implementation and availability of required resources, you can have copies made in parallel or sequentially.

Parallel copying

The number of FSE media pools assigned to an FSE partition determines the number of copies of the migrated data; you set up parallel copying by configuring at least two drives for the FSE partition (the MaxNumDrivesMigration variable in the FSE partition configuration file). Note that a media pool cannot be assigned to multiple partitions.

For best performance, there must be at least n drives free when the migration job with parallel copying starts, where n is the number of media pools assigned to the partition. Because of that, the number of parallel copies must not exceed the total number of drives that can be used for migration with the partition (MaxNumDrivesMigration), neither can it exceed the system-wide number of drives that can be used for migrations (SystemMaxNumDrivesMigration in the FSE system configuration file). Furthermore, the number of parallel copies must be balanced with the need for drives for other jobs running in FSE.

If there are not enough free drives available during a migration job with multiple copies, the copies that cannot be made in parallel will be made sequentially.

HP StorageWorks File System Extender Software user guide 147