Windows Server 2008 R2 Thread, IPv4 Checksum Offload in Technical; Hello all,
At one site I support I've setup a couple of 2008 R2 servers and joined them to an ...
24th June 2012, 08:47 PM #1
IPv4 Checksum Offload
At one site I support I've setup a couple of 2008 R2 servers and joined them to an existing 2003 domain. When transferring a 2GB file from 2003 to 2008 R2, the speed is pretty decent, however 2008 R2 to 2003 is extremely poor. I'm talking 2.5MB/s poor and the servers are connected at gigabit.
I've upgraded the Intel drivers on both 2003 and 2008 R2 servers and this did improve transfer speeds slightly, but they were still far too slow.
On the 2008 R2 servers, I then disabled IPv4 Checksum Offload and transfers from 2008 R2 to 2003 are considerably quicker and a lot more acceptable. Any idea(s) why this is happening? Is there anything else I could/should tweak? Many thanks!
24th June 2012, 11:21 PM #2
Could be screwing up the adaptive windowing, hd that alot with Vista to XP
Clint Boessen's Blog: Windows 7 Slow Access to Network Shares
It flares up under some network conditions when talking to older hosts. Lots on linux based NASs had issues with this and it this fix speed it up by around 10MB/s
netsh interface tcp set global autotuninglevel=disabled
25th June 2012, 12:14 AM #3
It's interesting because I've migrated many sites to 2008 R2 and 7, keeping 2003 and XP clients working together during the migration. Not once have I seen this behaviour.
As soon as clients are imaged to Windows 7, the problems go away. I've migrated the majority of workstations to 7, with only a handful left on XP. Still frustrating Microsoft haven't really made it 'properly' backwards compatible.
25th June 2012, 12:28 AM #4
As I say, it is only in very certain setups that it happens, it can be to do with network hardware, software/firewall stuff etc. I also have had many sites where this has not caused an issue but two places where it did, one with an SBS server and the other with a Seagete Blackarmor NAS. Both of these benifited massivly from the above reconfig. Never really figured out why it affected those sites and not others but they were much smaller than most of my sites so it was quicker to just fix it.
25th June 2012, 10:40 AM #5
This is just it, why some sites and not others. I can only conclude it's something to do with the NIC, the motherboard chipset or something else, rather than drivers.
25th June 2012, 10:44 AM #6
Also - I forgot to add, once you had migrated everything to 2008 R2 and 7, did you switch IPv4 Checksum Offload back on, on the servers? Or leave it switched off?
25th June 2012, 12:19 PM #7
I switched it all back on apart from machines that were running deep packet inspection like ISA/TMG or certain intel cards under Hyper-V untill the drivers got better.
Originally Posted by Michael
2003's TCP offload support was a bit hash even with the chimily support - or whatever they called it - there were equal odds of it being iffy in some situations.
Last edited by SYNACK; 25th June 2012 at 12:25 PM.
14th December 2012, 01:16 PM #8
@SYNACK - I've just come across this utility which turns MSI-X off. I'm going to give it a try later, as I'm still not convinced I'm getting the best speeds.
Thanks to Michael from:
SYNACK (14th December 2012)
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