[CentOS] How to stagger fsck executions

[Warren Young]

On Apr 21, 2015, at 3:12 PM, Warren Young <wyml at etr-usa.com> wrote:
> 
> With the four values that Kay provided, I calculate a 1.2% chance on average that two or more volumes will need to be checked on the same reboot.

Ooops, forgot to mention one other minor detail:

This calculator gives the chance or a 2+ volume simultaneous check, which is actually a much more stringent case than you ran into.  If you have four volumes and are using a relatively prime max-mount-count set, you won’t get a simultaneous check of all four volumes until your reboot count equals the *product* of all values in the set.

With Kay’s prime set, that means it won’t happen until you have rebooted 215,441 times.  If your machine lives 10 years, that’s enough to allow for about 60 reboots a day while still having *zero* chance of a 4-volume fsck.

I think it’s fair to say that Kay’s solution (or a relatively-prime set) does actually solve the problem.