I have a situation where we have Windows client using NTFS and some endpoint software which is storing stuff in alternate data streams (ADS) on the files. These files can be copied to and from XFS backed shares on the Unraid system without issue, however they fail on Btrfs backed shares. This is a problem because we run an XFS array behind a Btrfs cache. The reason that it works on XFS but not Btrfs appears to be that XFS has a larger extended attribute size limit.

So, a work around is to turn off the cache. Not ideal.

What I would like to do is to turn of ADS support on the server for certain shares, the data in the stream is transient and we don't care about keeping it. We don't however have a feasible option to do anything on the client side to auto scrub the ADS before writing to Unraid. My understanding is that you would typically use "streams support = no" in smb-extra.conf to disable ADS support on a SMB server. I however can't find any examples of doing this on Unraid, and when I try to set it the share gets set to unavailable.

smb-extra.conf

[MyShare]

streams support = no

Any suggestions? Thanks

I would not agree that xfs actively supports ADS.

Its just a side effect because it allows "up to 64kb of additional data" to be stored into the file.

Real ADS is not limited in size. So you may have already problems that you are not aware of. (ADS Data cut off)

The only filesystem with real ADS is NTFS, which will be available to UNRAID soon too (version 7.2 offers it for the first time).

But be aware too that ADS is a lame duck. Microsoft has already put it on their deprecated list, sooner or later it will be dropped completely. I only know a handfull of applications that ever used it although the "keep together what belongs together" idea was not bad. But users like it more to have a folder with several files to copy instead of one file with hidden subfiles.

I dont really understand your approach to disable ADS in the SMB config? If your cache strips it already, it never makes it to the xfs disks. So it makes no difference.

And, does your application still work without the ADS data?

anyway, you may take a look at https://www.samba.org/samba/docs/current/man-html/vfs_streams_xattr.8.html

Maybe this helps you with your problem?

Edited September 16, 2025Sep 16 by MAM59

9 hours ago, MAM59 said:

I would not agree that xfs actively supports ADS.

Its just a side effect because it allows "up to 64kb of additional data" to be stored into the file.

But be aware too that ADS is a lame duck. Microsoft has already put it on their deprecated list, sooner or later it will be dropped completely. I only know a handfull of applications that ever used it although the "keep together what belongs together" idea was not bad. But users like it more to have a folder with several files to copy instead of one file with hidden subfiles.

Agreed, but none the less the use of ADS and the content size is outside of my control and 64kb has proven to be sufficient. Microsoft tends to support deprecated features for an extended period of time, so support is needed for the forseeable future.

9 hours ago, MAM59 said:

I dont really understand your approach to disable ADS in the SMB config? If your cache strips it already, it never makes it to the xfs disks. So it makes no difference.

And, does your application still work without the ADS data?

cache does not strip. Attempting to write a file with a larger extended attribute than is supported by the file system results in 'disk full' errors. Yes, files are fine without the ADS data. The ADS data is related to endpoint security running on the client. That can't be changed so there isn't any point to go into further details.

9 hours ago, MAM59 said:

anyway, you may take a look at https://www.samba.org/samba/docs/current/man-html/vfs_streams_xattr.8.html

Maybe this helps you with your problem?

I've seen that and attempted to modify the configuration on Unraid. For better or worse the Unraid configuration is not coming from a typical configuration file like smb-extra.conf. As far as I can tell it gets cobbled together from Unraid internals and values entered in the Unraid UI. Perhaps more details on this are out there somewhere. As a result, my attempts to edit the configuration are overwritten as seen by inspecting the configuration of the actual running server.

you can put it into the smb-extra tab in the gui

Note 1: the array needs to be stopped before you can edit

Note 2: you need to supply each option into a seperate line!

like

these configs are saved and restored automatically after a reboot

(after edit restart the array to see the changes)