When/How do Boot Images Get Deleted?

[NASbox]

I upgraded to an SSD boot drive in 2017, and as I have updated my system several times I have collected a number of boot images.

Does the FreeNAS system prune these at some point in time? (If so/when)?
(From the manual it appears as if this would happen only if I run out of space.
Given the size of the drive, at the current rate, I'm good for at least a decade!)

I'm thinking that anything before 11-U6 isn't really needed. Am I taking any risk
by deleting the unused boot environments?
Any special order or procedure to follow? (Manual doesn't say anything.)

Anything special about default / Initial-Install?

Since 11.1-U7 is the current boot environment, what is "default"?

Here is my current setup.

Any suggestions/guidance would be much appreciated.

 

[Chris Moore]

Does the FreeNAS system prune these at some point in time? (If so/when)?

No, there is no automatic management of the images.
If you click on one of them, you will see a row of buttons at the bottom like this:

Just click the Delete button if you want to delete an image.

(From the manual it appears as if this would happen only if I run out of space.
Given the size of the drive, at the current rate, I'm good for at least a decade!)

My current boot pool was originally setup in a previous chassis and migrated forward along with the storage pool at the time.
I just let the images pile up. I used to delete them after they were six months old, but look:

I'm thinking that anything before 11-U6 isn't really needed. Am I taking any risk
by deleting the unused boot environments?

I don't see a reason to delete them, but there was no negative consequence when I was deleting them. At the time, I figured that if I had been on the new version for six months, I would not need to roll back, but I kept three previous versions or six months, which ever was more.

Any special order or procedure to follow? (Manual doesn't say anything.)

The manual doesn't say, because it is kind of optional, but I was deleting the oldest images first, just keeping the newest ones.

Anything special about default / Initial-Install?

Not really. These are ZFS snapshots, so just like with any snapshot, any blocks that are still in use will not be deleted.

Since 11.1-U7 is the current boot environment, what is "default"?

No. The one that is marked "On Reboot, Now" is the one you are using, right now. The "default" was from when you initially installed, before you configured anything, then the, "Initial Install", was probably created by the wizard and is what you had after the install was configured. Those can both go and it won't break anything.

 

[Chris Moore]

You shouldn't delete the one you are using. ;)

 

[NASbox]

You shouldn't delete the one you are using. ;)

Duhhh... you think so. ;) -- I guess it's worth mentioning just in case... I would think for safety, keep 2 at a minimum, although once you have upgraded your pools going back is not an option. Thanks for the very complete answer!