Group Queues: Sequential Profile Execution in SyncBack

Author: Swapna Naraharisetty, 2BrightSparks Pte. Ltd.

In SyncBack, a group, queue or group queue refers to a set of profiles executed in a pre-defined order.

The main differences between a group and a queue are outlined as follows:

Profiles within a group can be set to run either concurrently (in parallel) or sequentially, while profiles in a queue are run only in the sequential order.
When a group is run, the profiles within it are executed immediately, even if there are profiles currently in progress. Conversely, profiles within a queue are executed only when no other profiles are currently running. Thus, queues are useful in scenarios where constraints related to resources such as memory or bandwidth are present.

SyncBack V11 introduced the Group Queue, which combines the functionalities of both a group and a queue. Through the Group Queue feature, a profile can be added to a queue multiple times, offering enhanced flexibility. Furthermore, it provides the ability to assign a specific action to each profile in the group queue, such as running in simulation mode, initiating a rescan, or performing an integrity check on your files.

How To Create A Group Queue

Run SyncBack and click on the New button to create a new group queue.
Enter a name for your group queue, e.g. Group Queue.
Tick the options This is a group profile and Run profiles in a queue. Afterwards, click the Done button.

A notification will inform you that the Profile Setup window is about to appear. Click the OK button.
The Group Profile Setup window will open.

Now, you can include or exclude profiles from the group queue by using the <, <<, >, and >> buttons. Additionally, you can arrange the profiles within the group by choosing one or more profiles and clicking on the up and down buttons on the right.

Furthermore, you can customize the execution of a profile in the group queue. Simply right-click on the profile and select your desired option from the pop-up menu. For example, you can configure the profile in a queue to run in simulated mode.

Click the OK button to save the group queue.
Run the group queue to execute the profiles within it sequentially when no other profiles are running.

Important Things to Note

Since a profile can be added multiple times to a group queue, running a new instance of the group queue is possible even when the profiles within it are already in progress. However, this is not possible with traditional groups, as only one instance of a profile within a group can run at any given time.
Group queues do not support the inclusion of other groups.
Profiles within a group queue are executed in a sequential order.
When a group queue is scheduled, the profiles within it are executed at the scheduled date and time, instead of being added to a queue. This is because, the Windows Task Scheduler starts a new instance of SyncBack to execute a task, thereby eliminating the existence of a queue with profiles in it.

Profiles That Only Run as Part of a Group

A profile in a group or group queue is still an ordinary profile, and it can be started on its own in many ways: its own schedule, a hot-key, the tray menu, the command line, when a drive is inserted, and so on. That can be a problem if the profile depends on its group, for example because it uses the group's variables, or because it must run in a set order with the other profiles.

From SyncBack V12.1.34 you can stop this. Modify the profile and go to When > Group Only (shown in Expert mode). It has three options:

Only allow the profile to be run as part of a group
Only allow the profile to be run as part of a group queue (not in SyncBackFree, which has no group queues)
Allow the profile to be run as part of a visual group (via the main interface). In the main window, the profiles in a group are listed under it, and you can run one of them from there on its own. This is refused unless you tick this option.

If you tick both of the first two options, the profile runs as part of either a group or a group queue. If the group is inside another group, running the outer group also counts.

With one of these options ticked, the profile still appears in the main window and can be edited as normal, but any attempt to run it on its own is refused. That includes simulated runs, restores and integrity checks. A refused run copies nothing, and its result is Not Run (Group Only). It counts as a failed run, so any failure notifications (email, Pushover or webhook) are sent. From the command line, the exit code is -116.

SyncBack warns you about likely mistakes. When you tick an option on a profile that has its own schedule, it offers to delete the schedule. When you tick an option on a profile that is not in any group, it tells you the profile cannot run until it is added to one. When you save a group, it lists any profiles in it that will not be run, for example a profile that is only allowed to run as part of a group queue.

All three options are off by default, so existing profiles behave as before.

Watch the video on profiles that only run as part of a group, or read the When, Group Only help topic.

Conclusion