Download de HP agent for Xenserver from the HP site: HP Agent Look at the revision section to see if you have the latest version. Go to the ILO site of the host which you would like to update/install, open an Integrated remote console session. Mount the HP agent ISO to the server.
Last my XenServer where crashing randomly, we used Auto Support to look if something was wrong but nothing was showed. After some time looking at the difference between servers that where crashing and those that weren’t crashing I found that within the Smart Array controller I enabled “Write-Cache Battery Override”, after I Disabled this the servers weren’t crashing anymore.