C7000 fans question

[joeinca]

I just wanted to ping the community for some input on this if possible.  We received our c7000 a couple weeks ago along with 2 blades.  I've gone through the intial setup of the chassis, blades and interconnects and everything went pretty smooth.  One thing I noticed however is that with the 2 blades up and running, all 10 fans in the c7000 are operating at 89% and of course is pretty loud.  Regardless of what settings are set on the OA for power and thermal the fans remain at that speed.  Its only when I remove both OA modules -OR- power off both blade servers that the fans slow down to 29%.  All fans at 89% with only 2 idle blades seemed wrong so I opened a ticket with support....which brings me here because support seemed a little unsure at first if this was normal or problematic behaviour.  I worked over the phone with them for a few days on/off with this issue ...trying new settings, reseating OAs, upgrading AND downgrading firmware..then upgrading again to 4.5....all kinds of stuff.  They finally suggested we replace the primary OA and Sleeve and see if that changes anything.  

Today a technician showed up with a new sleeve that we he determined was defective.  He also had with him the incorrect OA device....so no changes were made today...he will return tomorrow with new parts to try again.  The field tech seemed to indicate 89% might be normal for 2 blades based on what he's seen but wasn't 100% sure...I'm just not buying that yet and can't seem to get a firm yes or no on this question.  My gut says there's something very overkill about 2 idle blades running in a chassis with all 10 fans blasting away at 89%.   Does anyone know for certain if this is an issue or normal behavior?  

Thanks,

Joe    

[Jimmy Vance · Accepted solution]

If required, the fans for the quadrant the blades are in will speed up, not all of them.  I have a couple of C7000 chassis with various blades loaded and the fans running at 35% and 47% . I wouldn't consider all 10 fans running at 89% normal with only 2 bldes installed

[joeinca]

Thank you for that feedback. I figured as much.