vfs_gpfs module

[Christof Schmitt]

On Tue, Oct 01, 2013 at 02:44:04PM +0000, Perez,Jaime R wrote:
> We are running samba-3.5.10 on a RHEL 6.3 box. Unfortunately, Red Hat
> does not support the module we need.  "This vfs_gpfs.so module is not
> shipped with Red Hat samba package .The basic idea about our support
> policy is 'if we ship it, we support it.' Therefore, this setup is not
> supported."
> 
> My question is, do we need this module to run or is there a work
> around?

The presentation at
http://sambaxp.org/fileadmin/user_upload/SambaXP2012-DATA/thu/track1/Christian_Ambach-Integrating-Samba-and-GFS.pdf
gives an overview of Samba/GPFS integration.

Without the GPFS-Modul from Samba 3.5, you lose sharemodes, leases,
usage of NFSv4 ACLs, get_realfilename and support for the creation
timestamp.

Sharemodes and leases are required if the same files are accessed
through Samba and through other means. If the files are only accessed
through Samba, they are not critical. Using NFSv4 ACLs internally should
be recommended since the POSIX ACL mapping from Samba to GPFS is not
widely tested. Another option for ACLs could be storing them in the
vfs_xattr_acl attribute.

get_realfilename provides a performance improvement since otherwise
Samba has to try all possible uppercase/lowercase combinations when
locating a file, and the support for the creation timestamp could be
important to some applications on the Windows clients.

Samba 3.5 is also not the newest branch, newer versions provide a better
integration into GPFS (see the presentation above).

I would say that it all depends on the exact requirements of the
applications accessing the data. If the mentioned features are not
important, you don't necessarily need the gpfs.so module.

> Since we already have samba running and we do not need an entire
> installation, how do we compile and exact only the vfs_gpfs module?
> 
> Using: http://ftp.samba.org/pub/samba/stable/samba-3.5.10.tar.gz

I have not tested this, and as Volker mentioned it raises the question
about support of this setup. Technically one option would be to install
the GPFS headers on the system, and then build Samba again from the src
rpm. This build should automatically create a gpfs.so module and be
close enough to the version currently used. Then locate the gpfs.so
module in the build tree, and copy it to the correct place in /usr.

> https://access.redhat.com/site/solutions/186233 Attempting to use the
> 'vfs objects = gpfs' option in smb.conf throws the following errors in
> samba logs [2012/08/10 10:58:56.718346,  0]
> smbd/vfs.c:167(vfs_init_custom) error probing vfs module 'gpfs':
> NT_STATUS_UNSUCCESSFUL [2012/08/10 10:58:56.718442,  0]
> smbd/vfs.c:309(smbd_vfs_init) smbd_vfs_init: vfs_init_custom failed
> for gpfs

The file does not exist, so this error is to be expected.

Regards,

Christof