JAVA VM Out of Memory - be careful with UBC
Proxmox UBC file location is

/etc/vz/conf/xxx.conf

Notice: Proxmox can rewrite this file when you are changing configuration from web interface!

kmemsize        5125208    5128321   40098656   44108521          0
privvmpages       77431      77666     750000     825000          0
physpages         44243      44371          0 2147483647          0

kmemsize: Kernel memory, used 5125208 bytes. Kernel memory keeps process information and cannot be swapped.
privvmpages: Private virtual memory (mem + swap in fact): ALLOCATED (but probably not used) 77431 pages (each page is 4Kb)
physpages: Physical pages: really USED 44243 pages of memory, out of what was allocated above.

tar cvpfz /linux.tar.gz * --ignore-failed-read --numeric-owner --exclude='*lost+found*' --exclude='proc/kmsg' --exclude='storage*' --exclude='var/log*' --exclude='var/spool/mail*' --exclude='usr/share/man*'

To another storage using 2 pass rsync

Jan 07 13:03:01 starting migration of CT 105 to node 'gis-xeon-1' (10.160.150.38)
Jan 07 13:03:01 container is running - using online migration
Jan 07 13:03:10 starting rsync phase 1
Jan 07 13:03:10 # /usr/bin/rsync -aHAX --delete --numeric-ids --sparse /var/lib/vz/private/105 root@10.160.150.38:/var/lib/vz/private
Jan 07 13:05:27 start live migration - suspending container
Jan 07 13:05:27 dump container state
Jan 07 13:05:29 copy dump file to target node
Jan 07 13:05:32 starting rsync (2nd pass)
Jan 07 13:05:32 # /usr/bin/rsync -aHAX --delete --numeric-ids /var/lib/vz/private/105 root@10.160.150.38:/var/lib/vz/private
Jan 07 13:05:38 initialize container on remote node 'gis-xeon-1'
Jan 07 13:05:40 starting container on remote node 'gis-xeon-1'
Jan 07 13:05:40 restore container state
Jan 07 13:05:52 removing container files on local node
Jan 07 13:05:53 start final cleanup
Jan 07 13:05:58 migration finished successfuly (duration 00:03:09)
TASK OK