[9fans] How to read fossil+venti partition without venti

[9fans] How to read fossil+venti partition without venti

[Pietro Gagliardi]

Hello. I'm trying to recover my files from the fossil+venti system I
have. I changed the configuration to read

	fsys oldfs config /dev/sdC1/fossil
	fsys oldfs open -AWPVr
	srv fossil

then do

	fossil/fossil -f /dev/sdC1/fossil
	mount /srv/fossil /n/oldfs oldfs

but when I try to get to /n/oldfs/active/usr/pietro/lib/profile, venti
spits out an error talking about "wrong score: not connected to
venti." Is there a way to get my files back without connecting to
venti? When it tries to connect to venti, I get an error saying that
service isn't found.

Thanks.

Re: [9fans] How to read fossil+venti partition without venti

[Bruce Ellis]

On Wed, Apr 23, 2008 at 11:48 AM, Pietro Gagliardi <pietro10@mac.com> wrote:
> Hello. I'm trying to recover my files from the fossil+venti system I have. I
> changed the configuration to read
>
>        fsys oldfs config /dev/sdC1/fossil
>        fsys oldfs open -AWPVr
>        srv fossil
>
> then do
>
>        fossil/fossil -f /dev/sdC1/fossil
>        mount /srv/fossil /n/oldfs oldfs
>
> but when I try to get to /n/oldfs/active/usr/pietro/lib/profile, venti spits
> out an error talking about "wrong score: not connected to venti." Is there a
> way to get my files back without connecting to venti? When it tries to
> connect to venti, I get an error saying that service isn't found.
>
> Thanks.

your data is on your venti, so no dice.

copy the venti partion (and fossil, if it's synced and quiescent) to
somewhere would be a good start with a really screwed up scenario.

brucee

Re: [9fans] How to read fossil+venti partition without venti

[Pietro Gagliardi]

No, my venti is not damaged. I just wanted to get some of my files
back. I'll try Steve's idea. But is there any way to bring up a venti
server read-only -- without it trying to sync or write blocks? (The
block-writing was the stage at which QEMU would crash.)

On Apr 22, 2008, at 11:21 PM, Bruce Ellis wrote:

> On Wed, Apr 23, 2008 at 11:48 AM, Pietro Gagliardi
> <pietro10@mac.com> wrote:
>> Hello. I'm trying to recover my files from the fossil+venti system
>> I have. I
>> changed the configuration to read
>>
>>       fsys oldfs config /dev/sdC1/fossil
>>       fsys oldfs open -AWPVr
>>       srv fossil
>>
>> then do
>>
>>       fossil/fossil -f /dev/sdC1/fossil
>>       mount /srv/fossil /n/oldfs oldfs
>>
>> but when I try to get to /n/oldfs/active/usr/pietro/lib/profile,
>> venti spits
>> out an error talking about "wrong score: not connected to venti."
>> Is there a
>> way to get my files back without connecting to venti? When it tries
>> to
>> connect to venti, I get an error saying that service isn't found.
>>
>> Thanks.
>
> your data is on your venti, so no dice.
>
> copy the venti partion (and fossil, if it's synced and quiescent) to
> somewhere would be a good start with a really screwed up scenario.
>
> brucee
>

Re: [9fans] How to read fossil+venti partition without venti

[Steve Simon]

> ...But is there any way to bring up a venti
> server read-only -- without it trying to sync or write blocks?

I am 90% sore that venti doesn not have a persistant cache of
blocks waiting to be written, so  if you boot venti alone it will
not write anything. What you are seeing as a "sync" is probably
a snap -a from fossil into your venti.

you should be able to start venti and then use vacfs to explore
your venti (run from from the live CD if you like). if you are happy
restoring this then you can reformat your fossil from this venti
and end up with a working system.

-Steve

Re: [9fans] How to read fossil+venti partition without venti

[Steve Simon]

Once you have run fossil with venti and it has done its first snap -a,
which is usually done after the first fossil+venti boot, you can now
never run fossil without venti. Fossil now contains only the files
which have changed since the last snap -a. All other files which have
not changed WRT the snap are reprisented by pointers (scores) into
the venti archive; This is fundamental to how fossil and venti work.

What you can do is run venti without fossil and extract your data from
there (using vacfs) provided you can get a score which reprisents the
root of the filesystem you are after (use fossil/last on your fossil
partition).

You can also completely repopulate your fossil as of the time of that
last snap -a losing only the changes between the snap -a and the time
your system crashed.

I wrote a "hold your hand" document, primarily for my own use, which
describes rebuilding a working system from only the venti arenas.

http://plan9.bell-labs.com/sources/contrib/steve/doc/Venti-rescue.pdf

I strongly suggest you print out the fossil and venti papers and manual
pages and read them carefully.

-Steve