Linux – New files on Linux Samba share: Now you don’t see me, now you do

distributed-filesystemslinuxnetwork-sharesambawindows

When a file is uploaded to our server, we have to do some work on it to allow or reject it.
Some files need to be opened in a Windows box (OpenXml Sdk performance reasons).
Our web server runs in a Linux box. There is also a samba share in Linux.
As a file is uploaded, php copies it to that shared folder so the new file can be accessed by everyone.
When the copy is done, php sends a message to the Windows machine saying:
Scan //Linux.Share.Ip/SharedFolder/FileJustUploaded.rtf

But we get a File Not Found !

If we poll the filesystems, the file appears in the shared folder as expected after short period of time (miliseconds to couple of seconds).

Let the shared folder be /opt/sharedFolder
Linux Ip: 192.168.1.10
Windows Ip : 192.168.1.11

At first, php was copying the files into /opt/sharedFolder.
In a try to make samba aware of the creation of the new file, we have mounted in /mnt/sharedFolder our own shared folder.

mount -t cifs //192.168.1.10/sharedFolder /mnt/sharedFolder

consequently php moves new uploads to /mnt/sharedFolder and then send the message to windows requesting Scan //192.168.1.10/SharedFolder/FileJustUploaded.rtf

No Luck 🙁

So, if i am getting this right, the Scan message makes windows request the file to samba before samba has broadcasted the existence of that file, hence the error.

Can we make something to prevent this from happening?
Can we change something to prevent this from happening?

Is there a "right way/best prectices" of doing this? I mean, using DFS or another filesystem (available in windows AND Linux) would fix this ?

Any suggestions are more than welcome.

Best Answer

It seems that windows mantains a cache for files and directories

With the release of SMB 2.0 in Windows Vista® and Windows Server 2008, three file metadata caches were implemented to speed up the return of the most recently accessed file and directory information. These caches also reduce the number of interactions a client requires with a SMB server for common file browsing operations. This has value in a scenario such as a client browsing a network file directory while connected via a low bandwidth or high latency connection. For common network file browsing scenarios, the default values are sufficient and should not be altered. Changing these cache timeout values can have significant performance implications to many network file scenarios. As each of these caches is designed to reduce the number of SMB server requests, they are important not only in client response time evaluation, but also in overall SMB server scalability and performance.

Changing the delay from 10 seconds to 0 using appropiate registry key seems to fix the issue. Now client lists files from server on every request instead of answering FileNotFount without checking the server... just because ten seconds ago it wasn't there.

Related Solutions

Linux – Migrating Windows shares to a Samba Linux based Share

The CIFS/Samba implementation in FreeNAS is excellent, we have several FreeNAS boxes and VMs going in an active directory enviroment, using AD for permissions on the shares. It's also extremely easy to set up and configure.

Once we've set up the FreeNAS box and enabled the CIFS/Samba service, we add the following to the 'Auxiliary Parameters' box in the CIFS service settings:

   client use spnego = yes
   winbind enum groups = no
   winbind enum users = no
   winbind separator = +
   winbind use default domain = yes
   wide links = no

Some of this may be unnecessary, but make sure to keep the 'wide links = no' in there as it mitigates a potential samba directory traversal vulnerability.

You can the create your shares. To set permissions via AD, we would add the following line to the 'Auxiliary Parameters' box for each individual share with the groups and/or users we want to have access to the share:

Valid Users = @OURDOMAIN+Somegroup @OURDOMAIN+'Some Other Group' OURDOMAIN+someuser OURDOMAIN+someotheruser

Note the groups preceded by '@', everything is separated by spaces, and groups or users with a space in their name are single-quoted.

FreeNAS installs and runs on FreeBSD rather than Linux, which allows it to include things like ZFS, but if you're determined to use Linux, OpenFiler is the Linux-based version of the same project.

If you do want to roll your own rather than use one of these distros (though they will simplify things for you immensely), you also might want to look into Likewise as an alternative to Samba for getting your box on the AD domain.

EDIT: Wow, sounds like you've got a lot of shares to migrate -- you may be able to script the addition of new shares, but be careful -- the smb.conf file gets overwritten from the /conf/config.xml file in FreeNAS each time the system restarts. You might be able to create the xml share definitions from your sharenum output to then paste into copfig.xml, using an example share you make as the template, but these get their own uuid from FreeNAS so I'm not sure how that will work -- I suggest experimenting after install and before you migrate.

Samba – Unable to see Samba server by netbios name

This is on samba 4.7.1

I was having the same problem as OP and alecov. Turns out, nmb service were not running.

You need to enable nmb separately from smb:

sudo systemctl enable nmb
sudo systemctl restart nmb

On samba 4 the service names is smb and nmb, somehow needlessly renamed making many available tutorials to be confusing (they are mostly based on samba 3).

Here is my smb.conf that works to enable netbios name broadcasting:

        workgroup = WORKGROUP
        netbios name = XXXXX
#       disable netbios = yes
        wins support = yes
        name resolve order = bcast wins lmhosts

You also need to check if it bind properly with your target adapter and the samba service is allowed in the firewall.

Best Answer

Related Solutions

Linux – Migrating Windows shares to a Samba Linux based Share

Samba – Unable to see Samba server by netbios name

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