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I'm experiencing extremely slow performance when trying to copy files from and to a samba 4 share. I'm using Debian and the Samba 4 SerNet packages and everything is up to date on the client as well as on the server. The connection is made through 100Mbp/s ethernet, but the problem also exists on a local virtual machine that runs on the Debian server.

By extremely I mean really abysmal:

  • Copying a folder with 50 files total size 10 MB to Win7: ~ 20 minutes at 3-4 Kb/s
  • Copying the same folder to Windows Server 2003: ~ 3 seconds
  • Copying a large random file 500 MB to Win 7: Takes ages to start copy progress than up to 10 MB/s
  • Copying the same large file to Windows Server 2003: Starts immediately to copy and takes a few seconds

I already googled for days and found a lot of suggestions to:

  • Changes switches: one of the test machines runs as VM on host, so this is not the issue
  • Update network drivers: same thing, using different machines and a VM the problem exists on all of them
  • Turn of Remote Differential compression on the client: Didn't help at all
  • Disable autotuning on the client with netsh: Didn't help at all
  • Make sure not to use mapped drives but UNC paths instead: Did help when logging in but has no effect on file transfer
  • Try switching max protocol on the samba server to something like NT1: did not help
  • Do not use any other custom smb.conf options like socket etc.

The only thing that seems to be working is using robocopy. With that, the 10 mb folder from above takes only a few seconds on Windows 7 too, but: I cant force my users to use robocopy from now on..... There must be a way to solve this!

Thanks for help!

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closed as off-topic by Ward, mdpc, Oskar Duveborn, womble Nov 8 '15 at 23:36

This question appears to be off-topic. The users who voted to close gave these specific reasons:

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I'm running samba4 from Wheezy Backports, the copying speed average is 40MB/s.

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Nope, it has not been an issue of any of these things. Rebooting the whole server did the trick for me, yet I still don't know the reason why this happened and how to prevent it from reoccurring! – schneida Jul 14 '14 at 17:14

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