[9fans] p9p and vac

[9fans] p9p and vac

[Paul Lalonde]

To amuse myself (and maybe even one day have backups) I decided to  
install a venti on a spare usb disk I had lying around, from my OS X  
box, under P9P.  That was fairly painless, and I now have a shiny new  
130 gig set of arenas to play with.
So I vac'd up some files, and then thought I'd try to get them back.
Has anyone had success with vacfs from p9p?  I've tried a simple '9p  
ls vacfs.vacfile' after starting the server and assuring myself the  
socket was there, but it simply hang there - no prompt until I  
interrupt the process.
Any ideas?

I also thought I'd try vbackup, but it really wants to run on an  
unmounted disk.  Of course, Macs come with their standard setup as  
one big partition with user files in the same partition as the system  
files - no way to do a backup with vbackup.
How difficult would it be to get a vbackup image from the same kind  
of walk as vac uses?

And lastly, what's the correct way to shut down venti?  Will I lose  
anything if I just eject (unmount) the drive?  I can force a flush  
from the web server - do I need to do that each time or is there a  
nice command line option somewhere?  Or do I just write the trivial  
script?

Paul

Re: [9fans] p9p and vac

[Latchesar Ionkov]

Hi,

There are few bugs in p9p related to 9P2000.u support that prevent 9p to
work with vacfs. I already sent a patch to Russ that fixes them.

The easier workaround that you can try if you don't wait for the bugfixes is
to change the version that 9pserve supports to 9P2000 (9pserve.c:219).

	Lucho

On Thu, Nov 17, 2005 at 11:23:45PM -0800, Paul Lalonde said:
> To amuse myself (and maybe even one day have backups) I decided to  
> install a venti on a spare usb disk I had lying around, from my OS X  
> box, under P9P.  That was fairly painless, and I now have a shiny new  
> 130 gig set of arenas to play with.
> So I vac'd up some files, and then thought I'd try to get them back.
> Has anyone had success with vacfs from p9p?  I've tried a simple '9p  
> ls vacfs.vacfile' after starting the server and assuring myself the  
> socket was there, but it simply hang there - no prompt until I  
> interrupt the process.
> Any ideas?
> 
> I also thought I'd try vbackup, but it really wants to run on an  
> unmounted disk.  Of course, Macs come with their standard setup as  
> one big partition with user files in the same partition as the system  
> files - no way to do a backup with vbackup.
> How difficult would it be to get a vbackup image from the same kind  
> of walk as vac uses?
> 
> And lastly, what's the correct way to shut down venti?  Will I lose  
> anything if I just eject (unmount) the drive?  I can force a flush  
> from the web server - do I need to do that each time or is there a  
> nice command line option somewhere?  Or do I just write the trivial  
> script?
> 
> Paul

Re: [9fans] p9p and vac

[Russ Cox]

> There are few bugs in p9p related to 9P2000.u support that prevent 9p to
> work with vacfs. I already sent a patch to Russ that fixes them.

Now in CVS.

Russ

Re: [9fans] p9p and vac

[Russ Cox]

> I also thought I'd try vbackup, but it really wants to run on an
> unmounted disk.

Did it tell you this or are you reading its mind?
I run vbackup on mounted disks all the time.
You may not get data that is written during the backups,
but quiescent data is preserved just fine.

> Of course, Macs come with their standard setup as
> one big partition with user files in the same partition as the system
> files - no way to do a backup with vbackup.
> How difficult would it be to get a vbackup image from the same kind
> of walk as vac uses?

You could just run vac instead if you don't care about having
raw disk images.  Vac has options to let you construct dump-like
trees (or other arbitrary trees) from multiple vac files.

> And lastly, what's the correct way to shut down venti?  Will I lose
> anything if I just eject (unmount) the drive?

[This is specific to the p9p version of venti, not the standard Plan 9 one.
Eventually this will apply to the standard Plan 9 one as well, but not yet.]

You won't lose data, because vac and vbackup sync before writing
to disk, but the next time you plug in the disk venti might take a
while to start up.  This is because venti knows it still needs to
index the recently written data and does so.

> I can force a flush
> from the web server - do I need to do that each time or is there a
> nice command line option somewhere?

You need to flush - flushdcache, flushicache, flushdcache.
Flushicache can take a long time.

Russ