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Our T610 server has 2 Gb NICs and a guest VHD thats 28GB in size. When I copied that VHD from our file server [Server 2003] to the local drive on hyper_v core it took over 3 hours.

This concerns me as I wanted to move backups back out to the physical file server but at 3 hours a go it could get messy.

I have tried ping -t -l 50000 serverip from hyper-v to physical - 9ms avg I have tried ping -t -l 50000 serverip from physical to hyper-v - 9ms avg

I ran the copy over weekend when there was no network traffic, both servers are on same switch. I don't often copy files that large across network so these may be normal speeds, can anyone advise?

I cant find a way to access the Hyper-V for advanced settings to check all is OK, I can access the server by connecting to it from computer management in Win XP/7 but when I view device manager it says denied, although I can see event viewer, shared drives etc!



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Ping isn't a good measure of much other than something being available that is configured to respond to a ping. ICMP doesn't follow the same rules as TCP, so it cannot be used to test a physical network config in this case. – MDMarra Sep 8 '10 at 1:51

28GB in 3 hours is about 2.6MB/s. That's really slow. Decent machines (especially servers with multi-spindle arrays) I would expect well over 100MB/s (which would have copied the whole 28GB in under 5min).

Therefore there is something wrong somewhere. Possibilities:

  • Source or destination machine was very busy
  • Hardware problem (e.g. bad network cable, just not quite bad enough to fail—this should show up for other network performance). Could also include a failing HDD
  • Initiating the copy from a third machine on a slow link (since all the data will via the machine that issued the copy command).

(That last one is very easy to do, makes little difference for small amounts of data so easy to just issue the command, done that one myself.)

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Hi Richard, thanks for the reply. Source is a HP server with GB NICs, SCSI disks, destination is brand new DellT610 8GB RAM, 2 x GB NICs, both machines had not other traffic as office is closed, only me logged in. Have changed switch port, cable and verified both machines drives are OK. Copied file while logged onto physical server, its very odd why so slow. When I disable large send offload on the physical server the speed does improve somewhat, takes 48 minutes to copy to my XP machine. Do you know I would disable large send offload on the hyper-v box NICs? – gary Jul 17 '10 at 10:12
Hi again, more testing throwing up some odd results. Disabled "Large Send Packets" on physical server and copied 28GB VHD across lan to physical DC, took 19 minutes! Changed registry settings on Hyper-V physical NIC to I think also disable "Large send offload", rebooted with no success? registry disabled LsoV1IPv4, LsoV2IPv4, *TCPUDPChecksumOffloadIPv4, *TCPUDPChecksumOffloadIPv6 Anyone got any ideas, this is driving me insane! Thanks – gary Jul 17 '10 at 11:53
@Gary, so what about coping from the Hyper-V host to the DC? It is just copying files between the Hyper-V Host and the File server? – Chris S Sep 8 '10 at 2:26

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