Dragoljub, this appears to be defect CSCeh41784 "CNR dhcp.ndb grows extremely large with ip history turned on", fixed in version 6.1(2.1). These are the release notes (incl workround) for this defect.
The default value of 0 for the visibility 3 dhcp attribute,
ip-history-trim-interval, disables ip-history trimming and
will cause the lease state database to grow without bound,
creating a huge dhcp.ndb file.
As a workaround, set this value to a small, reasonable value
such as 1 day.
For example:
nrcmd> session set visibility=3
nrcmd> dhcp set ip-history-trim-interval=1d
This will configure the server to run ip-history trimming
once a day, and delete any accumulated records that exceed the
ip-history-max-age.
Please make the changes suggested and monior the file size.
Matthew
