DAG 2013 facing DB1 MBX01 disk size issue?

HI

I have Exchange 2013 DAG with NLB with exchange CU7.

Suddenly we are facing issue on server DB1 disk is full and we migrate few users from dB1 to db2

it is recommended or not kindly suggest how to create free space on my exchange server MBX1.

and how to check which is my active and passive copy of the MBX1 and MBX2.

and i checked on the server circular logging is not enabled

Please suggest the same to resolve this issue.

Thanks

SW