Resilver priority and meaning in GUI. [TrueNAS-12.0-U1]

[jafin]

I'm a little confused with the language used relating to Resilver priority in the GUI.

The Checkbox in the tasks/Resilver priority note reads "Set to run resilver tasks between the configured times. "
The documentation says "The Resilver Priority menu makes it possible to increase the priority of resilvering at times where the additional I/O or CPU usage will not affect normal usage "

The checkbox language seems to infer that checking the box "allows" resilver to take place within the specified time window. But does it mean, like the documentation suggests, "to increase the priority of resilvering at times"

Is the checkbox note meant to say something more like "Set to run prioritised resilver tasks between the configured times." ?

 

[winnielinnie]

I would like to know too. Believe me, there's more of these "gems" of vague or seemingly contradictory descriptions sprinkled throughout the GUI and documentation.

To add to your question: What does it even mean to increase the priority? What does it actually do during those times? Does it lower the priority for other disk-related activities, such as shares, transfers, jails?

 

[winnielinnie]

Check out the wording from the official documentation of 11.3-U5:

Choose the hour and minute when resilver tasks can be started.

and

Choose the hour and minute when new resilver tasks can no longer be started.

Does that imply that attempting to start a resilver outside of that time-frame is not possible? Of course that's not true, since I have done a resilver outside of the time window I set under "Resilver Priority".

It's this type of ambiguous and non-thorough wording that can slowly erode someone's motivation to grasp the product in its entirety.

 

[Kris Moore]

It is a bit confusing to be honest, but what it means is that normally resilvers run as a very low-priority thread, so if your system is constantly busy, the resilver will happily run super-slow to try and avoid hurting main system performance. This scheduler lets you pick the times you want to bump up the priority of the resilver process, so that it completes faster. I.E. after working hours, weekends, etc.

 

[winnielinnie]

Thank you for the clarification!



So then would you agree it should read, as follows, in the tooltips and documentation?


Begin Time

Choose the starting time when a resilver process can run at a higher priority.

Hint: A resilver process running during the time-frame defined between "Begin Time" and "End Time" will likely work faster, as it is not being throttled to run at a lower priority. Keep in mind that it is advised to avoid putting the system under any intensive activity or heavy loads (replications, SMB transfers, NFS transfers, Rsync transfers, S.M.A.R.T. tests, pool scrubs, etc) during a resilver process.

and


End Time

Choose the ending time, after which a resilver process must return to running at a lower priority.

Hint: A resilver process running after this "End Time" will likely take much longer to complete due to running at a lower priority compared to other disk and CPU activities, such as replications, SMB transfers, NFS transfers, Rsync transfers, S.M.A.R.T. tests, pool scrubs, user activity, etc.

 

[Kris Moore]

Absolutely. I'm pointing this thread over to our Docs & Validation team so they can ensure that text gets updated to better reflect what this feature does.

Appreciate the heads up so we could clarify!

 

[diskdiddler]

Apologies to bump an old thread but are there *any* risks in applying this feature? Just how much faster is it generally?

 

[Kieros]

another bump as it is still not clarified when hovering over the question mark

 

[diskdiddler]

another bump as it is still not clarified when hovering over the question mark

Just so others know, I went for it, it reduced my times anywhere from 5 to 30% give or take, really saving my bacon on some 15 hour jobs finishing at 11:30, instead of middle of the night.

Finally, 6x16TB instead of 6x8TB in my machine.

 

[Kannderni]

Important question: Do I need to run resilvering even though I don't have any drive failure or didn't replaced any drive in the pool? I do have scrub task that runs every month so that would indicate if i have a problem.

 

[Davvo]

Important question: Do I need to run resilvering even though I don't have any drive failure or didn't replaced any drive in the pool? I do have scrub task that runs every month so that would indicate if i have a problem.

No, you don't. I suggest you reading this:

Introduction to ZFS

This is a short introduction to ZFS. It is really only intended to convey the bare minimum knowledge needed to start diving into ZFS and is in no way meant to cut Michael W. Lucas' and Allan Jude's book income. It is a bit of a spiritual...

www.truenas.com

 

[john60]

Absolutely. I'm pointing this thread over to our Docs & Validation team so they can ensure that text gets updated to better reflect what this feature does.

Appreciate the heads up so we could clarify!

This setting appears to have little to no effect.
Projects 8.5Hr for a 4TB drive, but after more than 8 hrs, still claims more than 2 hrs left to go.
CPU bounces between 6% to 15% (6 cores / 12 threads) before and after setting this flag.

Does this flag only work if set before the resolve process starts?

 

[sretalla]

Estimates are only that.

If you have a reasonably wide, relatively full RAIDZ pool, 8h (or even 10) is fairly quick for a resilver.

If that system is busy doing other things, you may find that setting speeds it up, but if the system is otherwise idle, no difference is expected with that setting.

Does this flag only work if set before the resolve process starts?

Since it's a time-based setting, I would expect not, it should just need to pass the start time of the window.