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verry slow backup over iscsi fiber network

Veaam is backing up over iscsi  switch - fibre - switch to vmware server. It goes verry verry slow 3 mb/s Everything is 1gb. When backup is started  follwing occurs in logging wireshark:

9146      10.0.0.100      10.0.0.217      22.709290      [TCP Dup ACK 9048#34] 49152 > iscsi-target [ACK] Seq=3721 Ack=15537069 Win=65392 Len=0      TCP


9421      10.0.0.217      10.0.0.100      22.713678      [TCP Fast Retransmission] iscsi-target > 49152 [ACK] Seq=15544693 Ack=3721 Win=61440 Len=1460      TCP


66751      10.0.0.217      10.0.0.100      37.572803      [TCP Out-Of-Order] [TCP segment of a reassembled PDU]      TCP

any help!
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loekvandenbrand
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loekvandenbrand
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1 Solution
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
do you have jumbo frames enabled, to improve throughput. They have to be enabled on the server, and your network switches neec to be supported and enabled as well.

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rfc1180Commented:
I agree with hanccocka that jumbo frames should be enabled, but I do not believe is causing your issue. Utilizing 1500 byte frames should get you at least 400-600Mbps and you are not even seeing that. I would suggest that you check the duplex settings for all switchports and servers to ensure that they all match (100/1000-full, or auto/auto). Additionally, if the network is congested, you will see TCP retransmissions as well. You will want to monitor the switchports utilizing cacti to gather statistics on the current throughput of the network or you can show interfaces to get a quick idea where the network is at now with the 5 minute input/output counters.


Billy
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loekvandenbrandAuthor Commented:
Thanks for the advice, Where do i need te enable jumbo frames? And how do i do that?
What to you mean with:

"You will want to monitor the switchports utilizing cacti to gather statistics on the current throughput of the network or you can show interfaces to get a quick idea where the network is at now with the 5 minute input/output counters."

Thx in advance!


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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
do you require ay further help with this question setting up Jumbo Frames?
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loekvandenbrandAuthor Commented:
thx
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