I'm interested in running a parity check every 3 months but cant figure out how to schedule that.  Here are the settings in Unraid

 

That's the closest I can get.  I select it for March, June, September and December, to start at 00:00 on the first week, but under "day of the week"  There is no "first day" option.  I only see days of the week like "Monday, Tuesday, etc" and those are always changing for the 1st of the month. 

With the above settings It seems like it will run it every day during the first week every 3 months (So it will run for 7 days straight).  Am I wrong here and this is just bad wording in the UNRAID GUI or does it actually work like this?

Set a specific day of the week, like this:

 

 

It results in this, the first Sunday of every second month:

 

 

 

But I want it to land on the 1st day of the month as thats when my users expect slowness and downtime as I run backups.  I guess the first Sunday will be the best I can do for now.  Maybe a future version of Unraid can add the option for first day

 

2 hours ago, 007craft said:

But I want it to land on the 1st day of the month as thats when my users expect slowness and downtime as I run backups.  I guess the first Sunday will be the best I can do for now.  Maybe a future version of Unraid can add the option for first day

 

 

A Parity check is a very intensive Disk IO operation.  You really want to avoid having it occurring at any time when you have planning another disk intensive operation as the additional disk head movement overhead will really blog things down.  And I would assume that your users are already seeing that from your comment!   (I even avoid trying to watch a BluRay IOS during the parity check.  DVD's playback is generally OK but I have experienced stuttering with BluRay material.) 

3 hours ago, 007craft said:

But I want it to land on the 1st day of the month as thats when my users expect slowness and downtime as I run backups.  I guess the first Sunday will be the best I can do for now.  Maybe a future version of Unraid can add the option for first day

 

You could use the Parity Check Tuning plugin to run the check in increments outside prime time thus reducing the impact on users (at the expense of a longer total elapsed time for the check).

So there's currently no way to have it execute on the first day of the month, unless it runs every month?

1 hour ago, KnifeFed said:

So there's currently no way to have it execute on the first day of the month, unless it runs every month?

 

The purpose of a Parity Check to assure that the hard drives that are being used in the array are not having any issues.  If a problem is detected, you want to find it when it is still a single point of failure!  Those are fixable.  If you extend the interval, you are more likely to find two points of failure and, while some are fixable, many more of those will result some data loss.  If one looks at it from a statistical standpoint, if you make the interval too long, you might as well not never do a Parity Check!

 

Remember if you suddenly get a read error when retrieving data from your array, you already have two points of failure!  At that point, you are beyond a simple repair procedure to recover your data.