I check /var/log & /tmp & /var/patch。
I also clean up the log files but it seems a little bit high usage on root disk。
So I use stupid way to check wht's the problem. XD
du -hs /*I found /opt is bigger than other system.
Finally I got the answear:DELL OMSA's log
/opt/dell/srvadmin/var/log/openmanage/dsm_om_connsvcdIO.logBackup up and clean it up.
I hope it all works out for you
/var/patch
/var/patch
/var/patch
/var/patch
Reference
XenServer Root Disk Maintenance
XenServer Root Disk Maintenance