I have a 3240 with a large number of CIFS shares. We occupy 3 suites within an office building, 2 of the suites can access the CIFS shares at normal gigabit speeds ~80MB/s transfer rates. Our newest suite is having issues, they only get 100KB-10MB/s transfers to the same files and shares. I tested access to Windows servers and those are all running at normal 80MB/s speeds. The network is the same in all suites, suite 1 is where the data center is with local users accessing files from a Cisco 2960S switch connected via 10Gb link to a Nexus 7010, then 10Gb into the NetApp, speeds here are normal. Suite 2 has a Cisco 3560G switch connected via 1Gb link to the Nexus 7010, then 10Gb to the NetApp, speeds here are normal. Suite 3 is the new suite, it has a Cisco 2960S switch connected via 10Gb link to the Nexus 7010, speeds here are slow, but in this suite I can access a Windows file share at 80MB/s but not to the NetApp CIFS shares.
I have upgraded/downgraded the code on the new suite 3 switch, doesn't help, I have enabled/disabled SMB2 on the NetApp, doesn't help. I have verified the QoS settings, switch uplink configs, switch port configs, all match the other switches within the network.
Can anyone offer other troubleshooting steps I could try to resolve this issue??
We don't have the same switch setup as you have but it seems like we're running out of buffers in our Fabric extenders. We saw packet drops on the interface connected to the server but not on the uplink to the Nexus. If you have drops on the uplinks the solution would be to add more bandwidth. To solve our problem the solution seems to be to configure the FEX to share the buffers "no hardware N2148 queue-limit" but it's not verified from Cisco yet.
Whenever I see a different speed between a windows server and a NetApp filer I first check the tcp windows size for CIFS on the NetApp. The default value for the NetApp is only 17520 and for the windows servers and windows 7 clients 2096560. Note that changing this value requires a disruptive restart of CIFS.
Since no one was posting on this I figured it out myself. Turns out the QoS settings on the 10G uplink of the new 2960 was the problem. I turned that off and everything started running the way it is supposed to. The werid thing is that it is enabled on the other switch that is also working fine. Either way, my users are happy and running at 10Gb, it was the QoS.