zfs discuss - Oct 2009 - Not a tragedy just a question

I''ve been running mirrored disks on several pairs of disks.  Mostly on
the advice of old timers here.

I wondered if I were to do something like 
 `rm -rf /$SomeUnexpectedlyEmptyVar'' flattening and removing
`/'',
 would I be able to retrieve it from the mirror?

I know about snapshots etc... but suddenly realized I don''t really
understand what security the mirror approach affords.  Or how to use it.

Harry Putnam wrote:
> I''ve been running mirrored disks on several pairs of disks. 
Mostly on
> the advice of old timers here.
>
> I wondered if I were to do something like 
>  `rm -rf /$SomeUnexpectedlyEmptyVar'' flattening and removing
`/'',
>  would I be able to retrieve it from the mirror?
>   
no, the system will happily do as you asked and remove the bits from 
both sides of the mirror.
> I know about snapshots etc... but suddenly realized I don''t really
> understand what security the mirror approach affords.  Or how to use it.
>   
You might think of it as roughly...

    mirroring helps protect you from hardware failure.
    snapshots help protect you from your own failure.

    -Norm