I have done a significant amount of effort working with Ethernet flow control on NetApp filers, Cisco switches, and HP blade enclosures with Virtual Connect modules and blades running ESXi and Linux. In the end, the NetApp whitepaper that made the recommendation to turn on flow control was rewritten.
Ethernet flow control is *evil*. Do not touch it. Ever. There's a reason the defaults are what they are and simply put, the folks that set those defaults know a heck of a lot more than those of us who think they might need to be changed.
Flow control on storage arrays are designed to protect exactly one thing: the storage array. They don't care what they do to the other end. The odds are really good that the only reason you think to want to change the settings is because something else in your network is broken. It doens't
There are LOT of pieces involved and you have to look at EVERY hop in your network since the flow control will ONLY work between segments. Once you've gone through a switch, the next segment needs its own settings. This isn't the old XON/XOFF of the good old days.
It also doesn't help you that there is no real standard - it's changing constantly so you have to fully understand exactly where in the standard life-cycle and what pieces of the standard each of your vendors (NIC, driver, switch etc.) have implemented their little piece. And then you have to follow that through the various firmware and OS updates since they're constantly changing.
jaychap
2 Posts
0
September 4th, 2014 11:00
Vlad,
Thank you for the suggestion. I will pursue that avenue.
Jay Chappell
Practice Architect
TRACE3
Cell: 303-919-7782
jchappell@trace3.com
www.trace3.com
Vlad_K2
7 Posts
0
September 4th, 2014 11:00
EMC KB (90125): How to enable flow control for a 10 GbE interface on an Isilon node
I would recommend to open Service Request because any sysctl's have to be modified by Isilon TSE only.
Anonymous User
170 Posts
1
September 5th, 2014 10:00
I have done a significant amount of effort working with Ethernet flow control on NetApp filers, Cisco switches, and HP blade enclosures with Virtual Connect modules and blades running ESXi and Linux. In the end, the NetApp whitepaper that made the recommendation to turn on flow control was rewritten.
Ethernet flow control is *evil*. Do not touch it. Ever. There's a reason the defaults are what they are and simply put, the folks that set those defaults know a heck of a lot more than those of us who think they might need to be changed.
Flow control on storage arrays are designed to protect exactly one thing: the storage array. They don't care what they do to the other end. The odds are really good that the only reason you think to want to change the settings is because something else in your network is broken. It doens't
There are LOT of pieces involved and you have to look at EVERY hop in your network since the flow control will ONLY work between segments. Once you've gone through a switch, the next segment needs its own settings. This isn't the old XON/XOFF of the good old days.
It also doesn't help you that there is no real standard - it's changing constantly so you have to fully understand exactly where in the standard life-cycle and what pieces of the standard each of your vendors (NIC, driver, switch etc.) have implemented their little piece. And then you have to follow that through the various firmware and OS updates since they're constantly changing.
Have I mentioned that you shouldn't go there?