Re: [9fans] venti

[Sape Mullender <sape@plan9.bell-labs.com>]

> i noticed something odd with venti and i am just trying to see if this
> is an issue and if this needs to be addressed.
>
> i think, by default, plan9 installation sets localhost as the address
> for venti in plan9.ini. but at some point i wanted venti to announce
> any (*) address. for some reason, i simply started venti/venti -a
> 'tcp!*!17034' to make it so. after this, i did vac from another
> machine and it archived data. after sometime, i realized i may be
> running venti on the same venti data area twice. when i did 'ps', it
> looked like that. then i rebooted the machine and then tried
> 'dumpvacroots.new' command (from contrib). i noticed that venti arena
> was corrupted. this is what i remember and if required i can try to
> reproduce the issue.
>
> the question i have is, is there any protection that prevents someone
> from doing this accidentally? something like the last active venti
> arena is marked 'IN_USE' so that if another instance of venti is
> started (with read-write access), it can check for this? i agree user
> has to be careful but given that venti archive is so critical, we
> should avoid any accidental damage.

Hmm.  Running two ventis on the same data is, of course, bad.  It's also
something I haven't seen happen before.  A check could be put in by having
venti put some sort of lock somewhere on the disk.  But that would lead
to problems if venti doesn't shut down properly: venti would be gone
but the lock would still be there.  You run the risk of not being able
to boot your machine.  I think you should just learn to be careful.

	Sape