The HMC version 188.8.131.52 introduced a new "Current Config Sync" feature that is very, very useful.
Anyone who has been working with Power Systems for long has been bitten by the fact that LPAR's saved "Profiles" and their "Running Configs" can get out of sync. For example, if you DLPAR some new Virtual Adapters to your VIO server, and forget to add them to the profile as well, you might have serious issues the next time you shut down and reboot your VIO server. This is because anything in the "Running Config" is lost when the LPAR is shutdown if it wasn't also added to the persistent profile. For several years, anytime you did a DLPAR change (such as adding/removing Memory/CPU's/Virtual CPU's/Virtual Adapters/etc.) you had to also make the same change in the profile or else you would loose the change the next shutdown/re-activation. This was such a problem that I created a extensive script that reports differences between the running config and the profile (see prdiff website for more info: http://prdiff.sourceforge.net/ )
A few years ago IBM introduced a very cool HMC feature that allowed you to "Save the Current Configuration". This allowed you to take the "Running Config" and save it to the profile overwriting whatever was there. This allowed you to make your DLPAR changes, then just "Save Current Configuration" to write the changes you made to the profile. This was a good step in the right direction, but still left room for error. If you forgot to "Save Current Configuration" after making a DLPAR change you would still have problems the next time you shutdown/re-activated the LPAR.
There is now a new "Current Config Sync" feature in HMC 184.108.40.206. This new feature is awesome and what everyone has been asking IBM for since DLPAR was first introduced..
If enabled, the "Current Config Sync" feature will automatically "Save the Current Configuration" anytime you make a DLPAR change. You don't have to do anything extra.. You just make your DLPAR change and it will automatically be Sync'd with the profile. Awesome!
The first thing you need to do is enable the "Current Config Sync" option. This feature is disabled by default (more on this later in the post). Start by clicking on the LPAR's name in the HMC window to bring up the Partition Properties. Right at the bottom of the general tab you will have the following "Sync current config" options:
By default, it is set to "Sync turned OFF". Change this to "Sync turned ON". Once you do this and click OK, the HMC will go ahead and "Save the Current Configuration" of the LPAR to the profile.
Next, lets make a DLPAR addition of a Virtual SCSI adapter:
OK, so we've DLPAR'd in Virtual SCSI adapter #9 with a Client Adapter #9 as well. We have "Sync Turned ON", so when we check the profile we can see that this new VSCSI adapter was automatically added to the profile as well, without any further effort on our part:
The Third Option - Sync Suspended until next Activation
You can either have Sync turned "On", "Off", or "Suspended until next Activation". You might be wondering when you would choose this third option to suspend the sync? This option is useful if you need to make changes to the LPAR that are not possible to make through DLPAR. For example, if you needed to change the "Max CPU" setting, you can't change it through DLPAR. This is where the "Sync suspended until next activation" comes in handy!
Lets suppose we want to change the "Max CPU" setting for the "aix1" LPAR which currently has the Sync feature turned "On". We can't DLPAR this change, so we pull up the partition profile and change the Max CPU to 0.8:
When you click "OK" you will get this message:
This message is letting you know that by changing the LPAR's Profile like this you are going to cause the profile and running configuration to be out of sync, and that this will cause the Sync setting to be changed to "Sync suspended until next activation".
Here is a screenshot that shows they are now out of Sync:
So from this point the "Sync" is disabled since you have made a change that caused them to be out of sync. The next time you shutdown and re-activate the LPAR to activate your new Max CPU setting the "Sync" setting will automatically get changed back to "ON" and everything will be back in sync again:
One-Liner to Mass-Enable this Feature
The only downside to this feature is that it is disabled by default.. Using the GUI to enable it requires clicking on each LPAR one at a time and setting the Sync option to "On". If you have a bunch of LPAR's this would take forever!
Here is a one liner command to enable the Sync option on ALL LPAR's on the HMC:
for frame in `lssyscfg -r sys -F name`; do for lpar in `lssyscfg -r lpar -m $frame -F name`; do chsyscfg -r lpar -m $frame -i "name=$lpar,sync_curr_profile=1"; done; done
Here is a command to check the status of the Sync option for all LPAR's:
for frame in `lssyscfg -r sys -F name`; do lssyscfg -r lpar -m $frame -F name,sync_curr_profile; done
It will show a "0" for "OFF", "1" for "ON", and "2" for "Sync suspending until next activation".
All I can say is "Well done IBM!" This is one of the most useful features added to the HMC in a very long time! If you haven't already, upgrade to HMC 220.127.116.11 and give this new feature a try.