Knowledgebase: Filesystem related
Speedup Slow SMB Mounted devices on Windows
Posted by Sven Koester on 18 September 2018 16:43
We described in another article how to make a network mount available to P5 on Windows, that was here:
   https://support.archiware.com/support/index.php?/Knowledgebase/Article/View/182/0/how-to-back-up-a-network-drive-on-windows

When reading from a NAS via Archive, Backup or Synchronize via SMB from Windows, there is a pitfall:

Windows doe not have a ctime attribute in the sense of that it shows modifications to the file attributes like Unix systems have.
So on Windows, P5 emulates a ctime attribute, maintained in an alternate data fork, that is written when the file's archive-bit is set.
This has two side effects in case the mounted file system itself is not a Windows NTFS system:
  • In case the mounted file system is also accessed from other OS, then this emulated ctime will also update the ctime attribute of the file that is shown on linux systems (this may depend on the details in the SMB server implementation).
  • Also, depending on the underlying file systems, the data fork may be stored not together with the file itself but may be physically located elsewhere on the storage. That means that when reading the emulated ctime attribute, additional disk head movements are required, and that in turn makes the access rather slow.
As a consequence, we suggest to turn off that ctime emulation when accessing non-Windows -hosts via SMB from Windows.

To do so, edit the file
    C:\Program Files\ARCHIWARE\Data_Lifecycle_Management_Suite\config\lexxsrv.8000
and  add the following lines to turn off the ctime emulation:
  ns_section ns/winSupport
  ns_param emulateCtime false
also, to turn off the comparison of ctime attributes during incremental backup, add
  ns_section ns/server/$server/module/LookupSelection
  ns_param testInodeChangeTime false

In Syncronize Plan, turn off  Additional Options -> Expert Setting -> Compare ... files by examining -> Owner and/or protection changes. 



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