Basically I am trying to find out where the difference in the rate of a network file copy might come from.

I have a virtual Server 2008 R2 SP1 and a virtual Server 2003 R2 SP2, using the same store, same amount of CPU and RAM. They are also on the same host running ESXi 5.5. New install on both, just installed all updates and joined the domain. Everything is on gigabit. They are both using vmxnet3 and the iscsi paravirtual driver.

When I copy a 4gb file from my windows 8.1 PC to the Server 2003 R2 machine I get this: server 2003 r2

When I copy the same file from the same computer to the Server 2008 R2 machine I get this: server 2008 r2

Why is the transfer to the Server 2003 R2 machine so much slower?


The reason is most likely that Sever 2003 R2 uses SMB 1.0, While Server 2008 R2 uses SMB 2.1. The linked article there has a table which shows what version of the protocol you'll be able to use with which client-server combinations. A connection to Server 2003 R2 will always be limited to SMB 1.0.

The newer versions of the SMB protocol include many performance enhancements, precisely because SMB, as initially released, suffered from slow data throughput.

General network stack improvements in Windows since Server 2003 R2 probably also have a noticeable impact, but the biggest single factor is going to be the difference in the SMB version used.


Did you use the defaults for the 2003 server's disk files? 2008 is smart and uses an aligned offset, 2003 does not so you do multiple IOs because the actual blocks on the storage do not align with the blocks inside the VMDK's NTFS file systems. It really does cause some big problems. n) Also 2008 does have some perf improvements so from a Win 8.1 box you get the advantages of SMB 2.1.

Between the two I'd expect a pretty big boost like you're seeing.

Server 2008R2 is SMB 2.1, not 3, so you'd be limited there. Sorry for the misinformation.

  • Is there anyway to align the blocks for 2003? – Enriquev Jan 30 '15 at 20:50
  • FYI, I was able to align the blocks. Did some more testing without much change to results. I guess the only thing left is smb2. thanks – Enriquev Jan 31 '15 at 22:33
  • It is. Old SMB is as bad as it gets ;) MS did a lot of improovements - 2012 is even better using multiple NIC at the same time when available. – TomTom Feb 2 '15 at 13:29

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