You may have plenty reasons to rename a TSM server’s hostname despite there is a risk. If you are going to do it, please make sure you follow the proper steps, otherwise you may screw things up.
In my test, I will disjoin my TSM sandbox server from the Sandbox.local domain, and rename it to TSM_Sandbox (same as the TSM servername).
The current hostname and domain.
1) Backup the TSM database.
set up the backup device class ‘set dbrecovery FILE’
backup the database ‘backup db dev=FILE type=Full’. The backup file is located in C:\Windows\system32
2) Stop the TSM service after the backup is completed
And change the service startup type to manual
3) Run the DB2 command to change the server name that is used by the DB2 instance.
db2set -g DB2SYSTEM=new_host_name
db2set -g DB2_EXTSECURITY=NO
db2set -all
4) Edit the ‘C:\Documents and Settings\All Users\Application Data\IBM\DB2\DB2TSM1\SERVER1\db2nodes.cfg’ file.
replace the old setting ‘0 LyncDirector LYNCDIRECTOR 0 ‘ with the new one ‘0 TSM_Sandbox TSM_SANDBOX 0 ’
5) Disjoin the domain and rename the host to TSM_Sandbox, then restart the server.
6) Check the hostname after the server is back online.
7) Run the following DB2 command.
db2extsec -a TSM_Sandbox\DB2ADMNS -u TSM_Sandbox\DB2USERS
8) Start the TSM server service and change the startup type to Auto
9) Run a test backup from a client. The TSM server is still working perfectly after the renaming 
10) Update the deployment engine by running the command.
c:\Program Files\IBM\Common\acsi\bin>de_chghostname.cmd
Jackie Chen's IT Workshop 