You can use the HMC lssvcevents command to view DLPAR event history. In the following example, I’m looking for “Add processor” related DLPAR events, over the last 30 days, for a specific LPAR.

$ lssvcevents -t console -d 30 | egrep 'Add processor|DLPAR' | grep s82861p22_nim

time=12/01/2016 00:48:33,text=HSCE2209 User name hscroot: DLPAR Add processor resources to partition s82861p22_nim succeeded on managed system Server-8286-42A-SN214F55V

Search for all DLPAR events over the last 30 days.

$ lssvcevents -t console -d 30 | grep -i dlpar

time=12/01/2016 00:52:27,text=HSCE2211 User name hscroot: DLPAR Remove processor resources from partition s82861p22_nim  succeeded on managed system Server-8286-42A-SN214F55V

time=12/01/2016 00:48:33,text=HSCE2209 User name hscroot: DLPAR Add processor resources to partition s82861p22_nim succeeded on managed system Server-8286-42A-SN214F55V

HMC Manual Reference Pages  - LSSVCEVENTS (1)

http://www.ibm.com/support/knowledgecenter/TI0003N/p8edm/lssvcevents.html