[users at i-scream] CPAN Sys::Filesystem on diskless AIX

[Jens Rehsack]

On 24.08.2012 10:41, David Lee wrote:
> Jens,

David,

> [A quick re-introduction.  About two years ago (Oct 2010) we were in
> contact about particular aspects of "Sys::Filesystem".]
> 
> I've now got a bug report for the ::Aix module.  But I should first
> point out that I'm not an AIX expert at all, by any stretch of the
> imagination.
> 
> A new AIX machine-cluster at our site is based on diskless nodes,
> whereas our previous AIX systems have all had local disk.
> 
> I put an existing perl application, that uses "Sys::Filesystem", onto
> this new cluster and we got some strange error messages concerning
> "lsvg".  We quickly tracked this down to module "Sys::Filesystem::Aix".
> 
> The module executes:
>    /usr/sbin/lsvg -Ll `/usr/sbin/lsvg -Lo`
> 
> This is fine on disk-based systems.  The embedded back-tick command
> produces one or more lines of genuine output; the surrounding command
> (with the "-Ll ....") can then process these lines.
> 
> But on a diskless system the embedded back-tick command produces zero
> lines of output; the surrounding command expects to see one or more
> lines, so complains:
> 
> ----
> 0516-992 lsvg: Illegal combination of command line options.
> Usage: lsvg [-o] [[-L] -n PVname]
>        lsvg [-L] [-i] [-P] [-m] [-M | -l | -p] VGname...
> Lists the characteristics of a volume group.
> ----
> 
> Could you investigate this, please?

I had a defect on my infrastructure machine storing my repository. I'll
try to get it online again as soon as possible. Please don't hesitate to
bug me again when I don't react soon.

As I don't have physical access on any AIX box at the moment, it could
take a bit longer to find an appropriate solution. I'm still unlucky
with the implementation on AIX.

My favourite implementation uses mntctl as you can see in
https://github.com/tdb/libstatgrab/tree/jens-mega-patch/
(https://github.com/tdb/libstatgrab/blob/53baeb77eb27d0296c676cf01a0cd4a5f8fd282f/src/libstatgrab/disk_stats.c)
line 745..1021.

I'm not sure whether I can access mntctl from Perl, if XS parts for
Sys::Filesystem might be interesting, ...

Please don't hesitate to write tdb at i-scream.org and/or
users at i-scream.org and ask for a roadmap to release next version of
libstatgrab (this can be used in Unix::Statgrab and therefore in
Sys::Filesystem, too - when available).

> Local impact and local workaround:
> 
> It so happens that our local impact of this bug is small at present. Our
> application would like to determine whether a filename is truly local or
> is NFS-mounted.  That is why it is calling "Sys::Filesystem". If it is
> NFS, it will attempt to process it in a slightly different way.  Our
> local workaround, which is OK for the moment, is simply to avoid
> "Sys::Filesystem" altogether on this platform and assume all files are
> truly local.

Well, without local disks, the assumption should be, none truly local,
shouldn't it?

> I hope that is enough information to outline the problem.  If you need
> anything else for it, let me know.  (If it gets into details of AIX,
> I'll probably pull a local AIX person into this discussion!)
> 
> -- David Lee