Minimum recommended free space

[blue1248]

Hello all,

I am estimating my storage needs for the next couple years and I used the calculator at this site - https://jsfiddle.net/Biduleohm/paq5u7z5/1/embedded/result/

As an example, I plugged in the following figures :
Drive size: 4 TB
Number of drives: 7
RAID type: RAID-Z2 (requires at least 4 drives)

I noticed the calculation for "Minimum recommended free space" of 3.936TB

I haven't come across this requirement in my research. Is this telling me that I must always have this amount of space unused in my vdev/pool? Basically, I am losing one entire drive? Is this correct?

 

[JohnDigital]

The recommended amount is 20%, but absolutely needs to be >10%.

 

[nightshade00013]

https://forums.freenas.org/index.php?threads/80-capacity-fill-rule-how-far-past-that-is-safe.39486/ will probably give you a good idea on that.

Basically you CAN fill it past 80% full but once you get over that especially with jails you will start having a risk of problems.

 

[blue1248]

Thank you.