NetBackup job delays
NetBackup jobs may be delayed for a variety of reasons. Common delays that may occur, and in some cases suggests possible remedies, are described below..
The NetBackup Policy Execution Manager (nbpem) may not begin a backup at exactly the time a backup policy's schedule window opens. This delay can happen when you define a schedule or modify an existing schedule with a window start time close to the current time.
For instance, suppose that you create a schedule at 5:50 P.M., and specify that at 6:00 P.M. backups should start. You complete the policy definition at 5:55 P.M. At 6:00 P.M., you expect to see a backup job for the policy start, but it does not. Instead, the job takes another several minutes to start.
The explanation is the following: NetBackup receives and queues policy change events as they happen, but processes them periodically as configured in the Policy Update Interval setting. (The Policy Update Interval is set under Host Properties > Primary Server > Properties > Global Settings. The default is 10 minutes.) The backup does not start until the first time NetBackup processes policy changes after the policy definition is completed at 5:55 P.M. NetBackup may not process the changes until 6:05 P.M. For each policy change, NetBackup determines what needs to be done and updates its work list accordingly.
Note:
For any one client, there is a limit of starting only one job per second . However, multiple jobs from different clients can be started within the same second. Depending on the configuration involved, significantly more backup jobs can be started within any fixed time period, which may change the performance behavior of the system. In some environments, you may need to change some configuration settings to achieve the optimum performance behavior.
If jobs are queued and only one job runs at a time, use the State Details column in the Activity Monitor to see the reason for the job being queued.
If jobs are queued and only one job runs at a time, set one or more of the following to allow jobs to run simultaneously:
Select to limit the number of read and write streams (that is, jobs) for each volume in the disk pool. A job may read or write backup images. If you select this property, you also need to configure the number of streams to allow per volume. When the limit is reached, NetBackup chooses another volume for write operations, if available. If not available, NetBackup queues jobs until a volume is available. In a product like Netbackup Flexible Scale (NBFS), this property is unselected by default. (that is, no limit).
Schedule attribute (should be greater than 1).
The general recommendation is to start with a value of 4 and gradually increase it until you find an acceptable balance for both backup and restores. See Media multiplexing (schedule attribute) In the NetBackup Administrator's Guide, Volume 1, for more information on Media multiplexing
Note:
Keep in mind that increasing this value may affect restore times. More information is available:
See How fragment size affects restore of a multiplexed image on tape.
Check the following storage unit properties:
Is the storage unit enabled to use multiple tape drives ()? If you want to increase this value, remember to set it to fewer than the number of tape drives available to this storage unit. Otherwise, restores and other non-backup activities cannot run while backups to the storage unit are running.
Is the storage unit enabled for multiplexing ()? You can write a maximum of 32 jobs to one tape at the same time.
Note:
Values greater than 4 may actually decrease overall performance because they may reduce restore speeds. More information is available:
See How fragment size affects restore of a multiplexed image on tape.
Note:
Be sure to check with the disk storage manufacturers for recommendations about your disk storage units.
For example, you can run multiple jobs to a single storage unit if you have multiple drives. (Maximum concurrent write drives set to greater than 1.) Or, you can set up multiplexing to a single drive if Maximum streams per drive is set to greater than 1. If both Maximum concurrent write drives and Maximum streams per drive are greater than 1: you can run multiple streams to multiple drives, assuming that Maximum jobs per client is set high enough.
Note:
All storage units that reference a specific MSDP pool have a maximum concurrent jobs setting. The total number of concurrent jobs for all storage units accessing a single MSDP pool should be approximately 10% less than the maximum number of I/O streams on the disk pool. This allows for secondary operations, like replications and duplications, as well as restores to be executed even during busy backup windows.
Tape jobs become active as soon as the resources are allocated.
NetBackup makes the tape jobs active as follows:
The NetBackup Job Manager (nbjm) requests resources from the NetBackup Resource Broker (nbrb) for the job.
nbrb allocates the resources and gives the resources to nbjm.
nbjm starts bpbrm which in turn starts bptm.
The job fails if no other storage units are usable, in any of the following circumstances:
If the media in a storage unit are not configured or are unusable (such as expired)
The maximum mounts setting was exceeded
The wrong pool was selected
If media are unavailable, consider the following:
Add new media
Or change the media configuration to make media available (such as changing the volume pool or the maximum mounts).
If the media in a storage unit are usable but are busy, the job is queued. In the NetBackup Activity Monitor, the "State Details" column indicates why the job is queued, such as "media are in use." (The same information is available in the Job Details display. Right-click on the job and select "Details.") If the media are in use, the media eventually stop being used and the job runs.
A job may be queued by the NetBackup Job Manager (nbjm) if the media server is not available. The job is not queued because of communication timeouts, but because EMM knows that the media server is down and the NetBackup Resource Broker (nbrb) queues the request to be retried later.
If no other media servers are available, EMM queues the job under the following circumstances:
The Activity Monitor should display the reason for the job queuing, such as "media server is offline." Once the media server is online again in EMM, the job starts. In the meantime, if other media servers are available, the job runs on another media server.
If a media server is not configured in EMM, regardless of the physical state of the media server, EMM does not select that media server for use. If no other media servers are available, the job fails.
To permanently remove a media server from the system, consult the "Decommissioning a media server" section in the NetBackup Administrator's Guide, Volume I.