ZFS cautions (pool flag additions committed)

[Ondra Knezour]

Dne 23.3.2014 18:50, Karl Denninger napsal(a):
> When ZFS code imports are brought forward that add feature flags there
> is a potential time bomb for existing users in that creation of a new
> pool becomes non-revertible (except read-only!) with regard to mounting
> on older revisions of the code.
>
> The same thing happens if you do a "zpool upgrade" of course, but at
> least that's an explicit act.  You might not realize that you're at risk
> on a pool create, however, unless you **carefully** scrutinize the flags
> that were on the last version compared against the current one.
>
> The primary "gotcha" here occurs if you don't upgrade your emergency
> boot media and for some reason you need to boot from a CD or USB key --
> you can be left SEVERELY screwed, and since -RELEASE is typically not
> rebuilt when this happens if you don't have a second machine laying
> around on which you can build a RELEASE image....
>
> I've caught this twice now since 10.0-RELEASE shipped and, while I
> haven't been bit by it, it serves as a caution because eventually
> someone tracking -STABLE is going to get badly hurt and be left with an
> unrepairable system.  IMHO there should be some sort of notice on the
> list when new zpool feature flags show up so you're fairly warned that
> building a new emergency boot media copy is required if you intend to
> track -STABLE on a continuing basis.
>

Excellent candidate for the /usr/src/UPDATING file?
-- 
Ondra Knezour