p-Class and c-Class server bay blanking panel use - mandatory?

[chuckk281]

It all started with a simple question from Richard:

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Just a quick sanity check. I've got a large  bank who is migrating across to a new data centre and as a big blade user, they are populating empty enclosures into the new DC first and then taking the blades across from old to new as appropriate. For both sites with large p-Class and c-Class deployments this is resulting in powered enclosures with empty bays as they move through this process. The question has come back on how critical is it that they utilise the server bay blanking panels on both enclosure types?

I know from the c-Class setup and install guide the description on the blanking panels is 'mandatory' and that makes a little more sense given the shared cooling approach in the enclosure however on the older p-Class I imagine there is less of a 'mandatory' requirement given the cooling is handled per server blade - but I'd be grateful for input from the field, should the recommendation be mandatory blanking panels for both enclosure types?

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Lots of input on this question:

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From Roger: 

The official word would appear to be, use the blanking panels.

From the C7000 Service Guide

FANS:

CAUTION:  For best cooling practices, do not operate the enclosure for extended periods with

more than one component or blank removed. When removing an active component, replace it

with a blank.

BLADES:

CAUTION: For best cooling practices, do not operate the enclosure for extended periods with

more than one component or blank removed. When removing an active component, replace it

with a blank.

From the p-Class Installation Guide

CAUTION: Always use blanks to fill empty spaces in enclosures. This arrangement ensures proper airflow. Using an enclosure without the proper blanks results in improper cooling that can lead to thermal damage.

From Derek: 

Much less so in the case of the c-class blades because of the anti- reverse flow louvres in the component bays

Definitely recommended in the case of p- class although this sounds like a good opportunity for them to make the jump completely to c-class - might we help with some kind of commercial consideration?

From David: 

Even with the valves on the c7000 that automatically close if a blade isn't in a bay (or the " anti- reverse flow louvres" as Derek calls them), there is a slight difference in airflow caused at the front of the enclosure when a blade isn't in a bay and the bay is left open.  The valves will make sure that air isn't stolen from actual blades that need cooling and that there's no feeding of warm air back to the front of the enclosure, but for permanently open bays the blanking panel needs to be used. 

I'd position to the customer that temporarily having an open bay or two on c-Class is okay, but a couple of blades in an enclosure and 14 open bays without blanking would be a no-no, and should be covered with blanking panels.  I'm going to make up a rule and say that even for temporary operation 80% of the bays should either have a blade or a blanking panel.

IIRC, p-Class doesn't have the air valve arrangement, so blanking panels are always in order, except for momentary operation while switching blades in or out of the enclosure. 

From Jeroen: 

Even more important with FlexFabric are the interconnect blanking panels on the backside of the enclosure; don't forget those!

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Lots of good input! Use it wisely.