Unsolved
This post is more than 5 years old
12 Posts
0
2751
VNXe 3200 and ESXi 5.5 Jumbo frame not working
My setup is a VNXe 3200 connected to a HP FlexFabric 5700 using SP A Ethernet Port 2,3 and SPB Ethernet Port 2,3 with 10GBase-T. The ESXi host is also connected to the FlexFabric at 10GBase-T. When I set everything to run at 9000 MTU, my ESXi immediately lost its connection to the datastore in the VNXe. According to VMware tech, they were able to ping the VNXe but the datastore will not connect. When I switch back the MTU to 1500, everything came right back up.
Any idea what is causing this problem and any work around?
Thanks
Vince
VinceTan
12 Posts
0
April 2nd, 2015 09:00
Thanks for the quick reply Holton. VMware tech actually try pinging with around 8500 packet size and it all worked without any issue. No lost packet at all. However, when back in ESX, it can see the device but will not mount the datastore.
HJEWKES
19 Posts
0
April 2nd, 2015 09:00
Vince,
The only thing that I can think of that could be causing this is, soemthing else in the network is not set to MTU 9000. The VNXe is picky when it comes to MTU and everything, VNXe, Switch ports, all ESXi virtual ports connected to the VNXe also need to be set to 9000. To verify this is setup correctly you can ping from the ESXi terminal to the VNXe server IP with a packet size higher than 8000 and if you get a return it is setup correctly.
Please let me know.
Thank you, best regards,
Holton Jewkes
EMC TSE
Swapnil_Chikhal
83 Posts
0
April 2nd, 2015 09:00
When 9000 packet size is set, You may try to ping from VNXe end as well.
- Enable SSH on VNXe from settings-->service system
- Login via putty with username: service
- Command: svc_networkcheck --ping --mtu 9000
Make sure that 9000 packet size is configure between both unit.
Regards,
Swapnil
VinceTan
12 Posts
0
April 2nd, 2015 10:00
I will try that on an off hour
VinceTan
12 Posts
0
April 2nd, 2015 10:00
Yes, the virtual switch is also set at 9000
AlvaroG
97 Posts
0
April 2nd, 2015 10:00
Do you have set the MTU to 9000 on the virtual switchs of VMware?
r_spiess
32 Posts
0
April 8th, 2015 05:00
First, double check if you have no packet fragmentation as already mentioned. This could also lead to anything from nonworking connections to strange behavior.
Do you use vSphere software iSCSI initiator or the ethernet card itsself as initiator?
I had an issue in the past with a 10GbE ethernet card with an integrated TOE. It showed exactly the same behavior as you have. After some investigation I found out that the ethernet card integrated TCP Offload Engine did not support jumbo frames at all (max MTU 1500). Although everyhing in the vSphere, network and storage was set up correctly it was impossible to mount iSCSI datastores to the ESXi Server. Even a Ping with MTU 9000 did work correctly, but iSCSI connection was impossible. If this is also the cause of your problem you have two options:
1) use vSphere software iSCSI initiator with jumbo frames.
2) use ethernet card with TOE initiator without jumbo frames.
Bye
Robert
VinceTan
12 Posts
0
April 8th, 2015 13:00
I am using the vsphere ISCSI software. The ethernet card that I am using is the Intel X540-T2.
I added another ESX host, this time a Dell R520 instead of the HP DL 360 Gen9, I set this server up with 9000 MTU for the ISCSI port. I also setup Ethernet Port 4 and Port 5 of my VNXe3200 with 9000 MTU. Same switch, different VLAN and different ip address range. It worked properly. I guess I will just have to schedule a downtime and try out the first server again with the 9000 MTU and see if I missed anything.
Thanks for all the help
Vince