[OpenAFS] verifying ro volumes are not taking up extra space

[Derek Atkins]

Lee Damon <nomad@crow.ee.washington.edu> writes:

> I have a vicepc partition that has a bunch of volumes each of which is
> rw with a shadow readonly.  When I do a vos listvol /vicepc of that server, I 
> see things like this:
> 
> m.r7.blacsmpich                   536872397 RW         12 K On-line
> m.r7.blacsmpich.readonly          536872398 RO         12 K On-line
> m.r7.blacsmpich.11                536872400 RW       1884 K On-line
> m.r7.blacsmpich.11.readonly       536872401 RO       1884 K On-line
> 
> I have a second /vicepc on a different file server with exactly the
> same volumes in it.  (readonly only, of course).  The second filesyste
> is only half as full as the volume with the rw and ro.  Both filesystems
> are 33GB formatted using ext3 formatting.

What metric/program did you use the test the filesystem usage level?
Using 'df' you should see that the file system with the rw and ro
should be _slightly_ more 'used' than the file system with only the
ro.  They shouldn't be the same (there is SOME overhead for storing
the ro volume), but it shouldn't be twice the size, either, on a fresh
release....

Note that if you're using 'du', then yes, you'll see twice the space.
This is due to the way 'du' counts links....

-derek


> I was under the impression that ro copies of a rw volume on the same
> vicep* slice should not take space, as they were merely ro pointers
> into the same filesystem unless the rw volume was modified and not
> released.  All volumes were released within the last 24 hours.
> 
> I created the ro volumes using the "vos addsite" command with no
> special flags.  (vos addsite <fileserver> /vicepc volume).
> 
> How can I verify that I've got this set up correctly?
> 
> The fileservers are both Red Hat 7.2 boxes running kernel 2.4.18-19.7.x
> and the 1.2.8 OpenAFS RPMs.
> 
> Thanks,
> nomad
>  -----------                       - Lee "nomad" Damon -          \
> work: nomad@ee.washington.edu                                      \
> play: nomad@castle.org    or castle!nomad                           \
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> Sr. Systems Admin, UWEE SSLI Lab                                   /  \
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> 
> 
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-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord@MIT.EDU                        PGP key available