MacOS – Xserve CPU Status LED’s under Mountain Lion

macosserver.appxserve

I have a dual Xeon Xserve, and a nagging issue. The Xserves have 2 small 8 LED arrays on the front, which show real-time cpu utilization (one array per CPU). Under Lion, these LED's would not become active until after you installed the Server.app. Currently under Mountain Lion, these LED's do not work at all, regardless if the Server.app is installed or not.

I figure that there has to be a way to see, or find out what in the Lion Server app is enabling these (a kext or something perhaps?), but I cannot figure it out. I tried comparing the system installed Kexts (/System/Library/Extension) before and after the server.app install, but did not find any new kexts.

Does anyone happen to know, or can provide any assistance in a way to dig down deeper on this? I know its not a show stopper, but its one of those things thats bugging me and I cant stop thinking about it.

Best Answer

It is possible to re-enable the front-panel LED array on the Xserve when running 10.8. It appears that the process responsible for displaying/updating the readout on the front panel is the hwmond process. Unfortunately, hwmond is not included with OS X v.10.8. However, it is possible to use the hwmond executable from a 10.7.5 system.

The hardware that I tested with was an Early 2009 Xserve. After copying hwmond from the 10.7.5 system into /usr/sbin, I copied the com.apple.hwmond.plist launchd configuration file from /System/Library/LaunchDaemons/com.apple.hwmond.plist, and installed into /System/Library/LaunchDaemons on the 10.8.5 system. After a reboot (or a launchctl load -w /System/Library/LaunchDaemons/com.apple.hwmond.plist), the system identifiers are working normally.

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MacOS – Can Mountain Lion be used as a guest OS under 10.7 Lion

As far as the license says, no.

You have the right to:

(iii) to install, use and run up to two (2) additional copies or instances
of the Apple Software within virtual operating system environments on each 
Mac Computer you own or control that is already running the Apple Software, 
for purposes of: (a) software development; (b) testing during software 
development; (c) using OS X Server; or (d) personal, non-commercial use.

So, as far as the license goes, you must already be running Mountain Lion in order to virtualize it.

MacOS – How to administer the Lion Server from a Mountain Lion client

This seems to be an instance where Apple's push for the latest and greatest causes real world IT issues.

Per Apple's support article, HT1822 - OS X Server: Admin tools compatibility information, using Server Tools for mismatched client and server OS versions just isn't supported:

To administer Lion Server from a client with a different version of OS X, connect to the server using Screen Sharing or Apple Remote Desktop. You can also use Workgroup Manager 10.8 on Mountain Lion to connect to Lion Server.

I'm not sure how useful Workgroup Manager is to you, but it may be of some value.

There's also using the command line tools over SSH, which may or may not be more desirable than Screen Sharing/Remote Desktop to you. Apple's Advanced Lion Administration guide has info on how to use the command line tools for most tasks

Best Answer

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