You can refer to this technote for the procedure:

Technote # 1144815: Moving a TSM Database Volume to another location. 

http://www-01.ibm.com/support/docview.wss?rs=663&context=SSGSG7&dc=DA430
&dc=DA440&dc=DA410&dc=D600&dc=DB560&dc=DB530&dc=DB520&dc=D700&dc=DB510&d
c=DB540&q1=move+db+log+define+extend&uid=swg21144815&loc=en_US&cs=utf-8&
lang=en



-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Thorneycroft, Doug
Sent: Tuesday, October 28, 2008 3:00 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] TSM Database 83.5 % Full

Look up define dbvolume in the Admin guide

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Yee, Julie Y.
Sent: Tuesday, October 28, 2008 12:56 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: TSM Database 83.5 % Full


Can you give me the exact command for define a new db volume??
How do I migrate the existing DB vol(D:\database\db1.dsm) to the new db
vol?? 
Do you have any detail steps of how to??
Thanks!
-JYY

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Zoltan Forray/AC/VCU
Sent: Tuesday, October 28, 2008 3:50 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] TSM Database 83.5 % Full

Yes, you must ALWAYS define either a new DB or LOG volume before you can
EXTEND/use them.



"Yee, Julie Y." <Julie.Yee AT JHUAPL DOT EDU>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
10/28/2008 03:24 PM
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To
ADSM-L AT VM.MARIST DOT EDU
cc

Subject
[ADSM-L] TSM Database 83.5 % Full






I got this message from daily report. TSM Database 83.5 % full

Copy 1 on D:\database\db1.dsm                            30 GB
Copy 2 on F:\database\dbcopydb1.dsm              30 GB

Copy 1 on D:\databased#######.dbv                7.5 GB
Copy 2 on F:\database\databased#######.dbv 7.5 GB

q spacetrigger db f=d got the following output:
DB full Percentage:              90
DB space expansion percentage: 25
DB expansion prefix: d:\database
DB Maximum size (Megabytes): 0
Mirror prefix 1: f:\database
Mirror prefix 2:

Only  4 GB of space left on D drive.
 3.5 GB of space left on F drive.
How do I Extend DB ?? Do I need to define db volume first??

Please advice!