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Wednesday 31 July 2013

The Case of the Really Slow vCenter Logons

My latest client had implemented vSphere 5.1 by themselves.  They had done a good job, following some in depth architectural processes. 
All was working well and the infrastructure was hosting a relatively small amount of production VMs successfully.
The only thing was, that authentication to vCenter was taking an incredible amount of time.  They were using SSO (as it was vSphere 5.1) to authenticate against a large, multi-domain AD forest.

Using the:
Measure-command {Connect-viserver –server *****} command I got a decent benchmark:

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 238

238 seconds!?!?

My initial thought was that the slowness was solely due to the fact that the Domain Controller used to authenticate against was located in a different country, accessed across a WAN link.  Changing the identity source to a local DC would surely make a huge improvement?  I made the relevant changes in SSO to point locally and ran the command again:
 
Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 36

 
Better! But not good enough..
I scratched my head for a few more days, until I began thinking about the level in AD SSO was searching at.

If SSO had to wade through hundreds of thousands of AD objects to find the User Group Membership, of course it would take a while.  So I checked the Base DN for Users and Base DN for Groups fields in SSO Administration and sure enough they had both been set at the very top level of the domain.

I queried AD to find which OU the groups and vCenter users were located in and entered this DN (Distinguished Name) in to the Edit Identity Source form.
I ran the measure-command again and got:

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 6

That’s was more like it! 

 

NB: If you decide to make this change, make sure you put some thought into where the OU is within AD.  You don’t want to end up specifying an OU that’s too deep within the AD structure meaning that you exclude some of the people who should be logging on!

 

Chris.

 

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