ODBC database on Samba share. File locking issue?

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flyer
Posts: 7
Joined: 2010/01/01 19:46:29

ODBC database on Samba share. File locking issue?

Post by flyer » 2012/02/07 21:42:36

Hi,
our CentOS 6.2 server runs an old-styled ERP working with ISAM files as a database.
Through ODBC we can access from Windows (MS Access) the ERP database wich resides on a Samba share on the CentOS machine.
With our previous Linux server, based on an old Redhat release and an accordingly old (10 years) Samba version, this configuration has worked flawlessly for a decade.

Now, with the CentOS server, the following happens:

Running a MS Access application from Windows after the CentOS server has booted, but BEFORE any user on the server has accessed the ERP database, everything works fine.
To give a figure, a MS Access application we currently use takes 20 seconds to complete.

Running the same application AFTER any user has accessed the ERP, it would horribly slow down to 4 minutes.
Even if all the CentOS users log out, the problem remains and all I can do to momentarily fix it is reboot.

The network speed, checked by copying large files from Win to the Samba share and back, is always at a reasonable 50MBytes/sec.

I've thought about a locking issue on the ISAM files over the Samba share and, since I only need READ access from Windows, I've tried "locking = no" in smb.conf for the Share but nothing has changed.

Hope I've made myself clear enough.
For the men of good will, here are all the relevant info on my system:
[url=http://pastebin.centos.org/38351]getinfo.sh[/url]
[url=http://pastebin.centos.org/38352]smb.conf[/url]

I've also played around with dozens of Samba options to no avail. I'm pretty desperate...
Thanks to anyone has had the patience to read up to here!

flyer
Posts: 7
Joined: 2010/01/01 19:46:29

Re: ODBC database on Samba share. File locking issue?

Post by flyer » 2012/02/08 15:22:13

I forgot to mention that my NIC is a Realtek (RTL8111/8168B) and I have read about weird behaviour of this network card under Linux.
Could this be NIC-related?

pschaff
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ODBC database on Samba share. File locking issue?

Post by pschaff » 2012/02/09 16:09:29

I have no experience with Samba as a server for an Access database or locking issues, but if you suspect the NIC then [url=http://elrepo.org/tiki/kmod-r8168]ELRepo kmod-r8168[/url] is worth a try.

r_hartman
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Re: ODBC database on Samba share. File locking issue?

Post by r_hartman » 2012/02/10 07:35:35

Well I wouldn't expect the NIC to be a part of it, but more the ancient software.

Just thinking out loud here:
The RedMontCompany has made a number of OpportunisticLocking changes since releasing XP, causing me lots of issues with the iSeries IFS (basically a Samba implementation) that required PTFs (patches) to adapt the iSeries behavior to the M$ changes. Something in the order of applying and releasing locks was changed, causing issues with the use of MS Office (the lock files were never cleaned up anymore, and they could not be deleted until after some time). You may be looking at something similar.

As you're coming off a 10 year old OS with a 10 year old application, the old Samba may not have bothered with the M$ changes as it was read-only access anyway, and now the new Samba does while the old ERP application will still use its own possibly incompatible locking scheme. Sometimes it's best to leave museum-grade applications on museum-grade hard- and software. (Having said that, I know that some iSeries (AS/400) stuff I developed in 1996 is still running today).

However, if the ODBC app completes OK, but just a lot slower, it must be suffering from timeouts on 'something'. Maybe putting a trace on the ODBC app, if possible, can reveal what that 'something' might be? If it's XP's opportunistic locking mechanism clashing with your ERP app's locking mechanism, you may be out of luck.

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