Reply from support:
Create multiple partitions on nand with this command, it will reboot router and create selected count of partitions:
/partitions repartition partitions=2
This command will copy current partition content to secondary partition. Content is considered RouterOS and configuration:
/partitions copy-to partition=part1
Or if paritions have already been created and you want to simply copy most recent configuration to backup partitions then use command:
/partitions save-config-to partition=part1
To activate specific partition use command (this can also be done from bootloader):
/partitions activate (number or partition name)
Partition size is selected automatically by system.
After repartition:
[admin@RB951G-2HnD] > partitions print
Flags: A - active, R - running
# NAME FALLBACK-TO VERSION SIZE
0 A part0 next RouterOS v6.1 Jun/12/2013 11:50:54 64MiB
1 R part1 next RouterOS v6.1 Jun/12/2013 11:50:54 64MiB
In the root menu Partition you could Repartition (size is determined by the system). After Repartition to the desired number of partitions the system will be rebooted. You have to have space for the number of required partitions on your flash (see http://wiki.mikrotik.com/wiki/Manual:Partitions).
After reboot, stay on active partition and Copy-To the new empty partition. Stay on the partition with working setup and “Save-Config-To” different partition you wish.
In the menu “Partitions” right-click and choose “Activate”, then reboot (menu System - Reboot).
Update your running system (menu System - Packages), reboot and test. In case of trouble, activate old configuration and reboot.
If you would like to test new version, do not forget to copy your active/good setup to the backup partition first and THEN upgrade+reboot+test new version.