4G is unlikely to work well.
You are installing a copy of DB2 (for the TSM server) and a copy of
Websphere (for the admin center) under the covers.

If you are planning a small installation and don't have any very strict
timing windows to meet (and they haven't put in any size checks in the
6.2 install package that prevent you from installing it), you can
probably get it to work OK by installing the admin center and reporting
component on a different machine (those pieces can even be on a VM).

By "small", I'd say 50 clients or less, 500G per day or less --and those
numbers are pretty arbitrary on my part.
I'm just basing it on the fact I got the admin center and TSM @6.1 to
install on my 4G laptop. 

But, RAM is needed for I/O buffers as well.  
TSM is not CPU intensive, nor is the server itself very memory
intensive.  It's all about I/O.
YMMV
 

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Dana Holland
Sent: Thursday, April 22, 2010 10:13 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] Tivoli newbie

We're about to set up TSM for the first time.  I was surprised to see in
the installation guide that 12gb of RAM is required for 6.2  The server
that we were planning on using only has 4gb - it's an IBM 7026-6H1 -
with a 2-way 1.2ghz power4+ processor.  I don't see anything in the
installation guide that mentions requirements for processor power.  Does
anyone know if this server will be sufficient?