Question about scheduled scrubs

[Fritzolio]

Do they occur every 35 days or every 35 days of runtime?

Thanks

 

[Mr_N]

every x days depending on what you set as x, runtime doesnt come into it.

 

[danb35]

It's based on calendar days, not days of runtime, but it's a little more complicated than just "every 35 days". The default scrub runs once a week (and I don't remember the time or day, so for the sake of discussion, let's say it runs at 1:00 Saturday mornings), and it has a threshold of 35 days, or 5 weeks. The threshold measures the time since the last scrub completed (or since the pool was created, if no scrub has been completed), and if that time is less than the threshold, the scrub doesn't run. The scrub, of course, takes some non-zero amount of time to run. So let's say it ran Saturday morning, 2 Jan, at 1:00, and took an hour to run. Five weeks from then, on 6 Feb., at 1:00 AM, the script will run, check the threshold, and see that it's been less than 35 days since the last scrub finished (it's been 34 days, 23 hours), so the scrub won't run. The following Saturday morning, 13 Feb., the scrub will run.

What all of that means is that the default schedule actually works out to a scrub every six weeks.

 

[Fritzolio]

Last time a scrub ran was Nov 28th. It's been more than 35 days. Settings are still the default.

 

[danb35]

Expect the next one to run tomorrow.

 

[Fritzolio]

Thanks.

 

[Fritzolio]

Scrubs occurred last night as predicted. :)

I think I understand now how it works. Scrubs occur on a Sunday unless otherwise scheduled.

 

[Mr_N]

yeah if its set to go at 1am on a sunday every calendar sunday it gets to it checks has it been more than the threshold days since last scrub, if yes it scrubs if no it does nothing until the next sunday.

 

[Fritzolio]

Thank you sir. I'm becoming more FreeNAS aware every day. :)