9.3 Queue creation

A queue is a way to control job execution on a target. A queue can be closed to stop jobs which are submited in this queue. A queue can also be used to control the number of jobs which are running in the queue at the same time.

A system queue `batch' exists for each target, this queue can't be deleted.

In this example, we will add three queues `save', `system', `normal' on the `localhost' target. We will use the qa command to add a queue, the qsd command to set the queue description and the ql command to print the queue list of the target :

$ dio87c -- qa localhost save
$ dio87c -- qsd localhost save "queue for save on tape"
$
$ dio87c -- qa localhost system
$ dio87c -- qsd localhost system "queue for system jobs"
$
$ dio87c -- qa localhost normal
$ dio87c -- qsd localhost normal "queue for other jobs"
$
$ dio87c -- ql localhost -d
batch
save       queue for save on tape
system     queue for system jobs
normal     queue for other jobs
$

You can control the maximum running jobs in a queue. For example, if you have 2 tapes to do the saves, you can set the maximum running jobs to 2 for the `save' queue. If 3 saves comes in the queue at the same time, the first and the second jobs will be started and the third job will be holded. When one of the running save terminates, the third job will be started.

For example, we will use the qsm command to set the maximum running jobs of the `save' queue on the `localhost' target. Then we will use the qi command to verify that change is OK.

$ dio87c -- qsm localhost save 2

$ dio87c -- qi localhost save  
Target Name:  localhost
Queue Name:   save
Description:
Max:          2
$ 

A queue could be closed : new jobs in this queue will be holded until the queue is re-opened.

For example, it will be useful to close the `save' queue if a tape is out of order.

We will use the qso command to close the `save' queue, use the qi command to verify that queue is closed, and use the qso command to re-open the queue :

$ dio87c -- qso localhost save false 
$ dio87c -- qi localhost save
Target Name:	localhost
Queue Name:	save
Description:	queue for save on tape
Opened:         FALSE
Max:            1

$ dio87c -- qso localhost save true
$ dio87c -- qi localhost save
Target Name:	localhost
Queue Name:	save
Description:	queue for save on tape
Opened:         TRUE
Max:            1

Now, you know what are targets and queues and how to create it.