Uneven traffic with PowerPath

Question

Hey guys,

I've been looking through our SAN traffic, which contains two separate Fabrics, each with core Cisco MDS9513 (with the DMXs are attached to) and edge MDS9509 switches (with hosts attached to). I've noticed that some windows hosts with PP installed do not split the traffic between the two Fabrics...

I've checked PP, license, policy (SymmOpt), ISLs, HEAT report was ok too. One of the hosts is even a part of a cluster which is connected the same as the other host, but only one of them do not split traffic. Traffic on those "problematic" hosts ranges betweem 5% on 1 fabric and 95% on the other and sometimes 20%-80%... All other 300+ hosts usually split it even at 50%-50%.

Any ideas?

Thanks,
Maxim

RRR · Answer

Traffic on those 'problematic' hosts ranges betweem 5% on 1 fabric and 95% on the other and sometimes 20%-80%.Ok, so you ruled out the possibility that perhaps 1 zone is missing or 1 HBA is broken.Hmmmm

MaximUnited · Answer

Yeah. Zones and masking are ok. PP shows both paths alive and active.What can it be?

SKT2 · Answer

How is the connection of problematic host in the SAN? Does this host hav two core connections or routed thorugh ISL? ISL connections may give load balance problem unless the truncking license is available.

can you post "powermt watch " from the problem host. This will give the IOs over each paths/HBA

MaximUnited · Answer

It is connected to the edge switches, while the storage is in the core.
Meaning yes, the traffic goes through the ISLs which are trunked.
But like I said, I have about 300 other servers that are connected the same way.
Some of them are connected to the same FAs.

Somehow, whenever I login to the server, the 'powermt watch' shows 0 i/o. which is weird

I'm also troubled that all problematic hosts are windows.
Haven't seen this on Linux, HP, AIX, Solaris or VMWARE... :S

hersh1 · Answer

And you have 4/4 paths for each device? I had an issue where all 4 paths were logged in and registered with the array but only 3 paths were being used on the server. I would see the same utilization as you were.

hersh1 · Answer

Thanks, I completely missed that.

MaximUnited · Answer

Not 4/4.Just 2/2

RRR · Answer

He's connected to Symm, not CX, so that would be 2 HBA's, 2 FA's thus 2 zones.

MaximUnited · Answer

So does anyone have an idea?

dynamox · Answer

anything funky in HBA configuration ? throttle settings, queue depth, topology ?

MaximUnited · Answer

I wish...Not that simple Both EMCreports and manual check confirmed EMC settings...

RRR · Answer

Something weird in the switch ? Perhaps 1 port is set to 1Gb instead of 4 ?

MaximUnited · Answer

Actually I forgot to check the speed. Thanks RRR. But this is not the case.All HBAs sync at 2gbs.

MarkF4 · Answer

Are you seeing similar numbers of queued IOs on each path? Or does one of the paths seem to always have a couple of IOs sitting on a path while the other fluctuates?

dynamox · Answer

i know this is not the most desirable way to fix thing but have you tried re-installing PP ?

PowerPath

Uneven traffic with PowerPath

Was this post helpful?