How to extend the dedup diskpool without data migration?

Yes extending dedup disk pool is possible and descriped in the Deduplication Guide,

basically you stop netbackup on the media server containing the dedup disk pool, extend the volume, start netbackup on the media server.

Have done from 32 TB to 48 TB, without any problems.

The person that has written that technote, seems to have forgotten about dynamic disk in windows. Know it is not much used, but has been a feature since Windows 2003

Not the precise size, but have heard same front end data (1 full of all systems) and 60% of front end data

I disagree with using a simple calculation, which can easily catch you out.  The size of your dedupe pool is dependent upon several other and very different factors.  Not necessarily the size of one full plus one other factor.   It is initial uniqueness (i.e. not initial size) + rate-of uniqueness (i.e. not rate of change) + retention...    which determine the size of dedupe storage.   N.B: the longer you retain in dedupe the more likely it is that the oldest backup data becomes more unique (and apparently swells in size although you can never see it).   Dedupe requires a completely different thinking hat on.

If you really need a tool and want to see how one should approach it - then ask your Veritas TAM whether he/she can spend an hour on-site with you to model it in their calculation tool.  If your TAM is kind, and has time, get them to dig in to the Excel cells that sit behind the calculations and show them to you - and you'll see some cells with over 100 cross references to other cells and multi-level nested IFs and Elses... all very very complicated.

Remember, the reason this tool can never be made public is because no-one can ever swear by it... because it all comes down to how unique your data is... and this is very very dificult to model accurately - and so the tool will never be, and can never be, released... because unscrupulous customers will use it to challenge a vendor when customers get it horribly wrong and need to find someone else to blame.  This isn't Veritas being cagey.  No sensible vendor is going to publish tools which, by the very nature of the paradigm that is dedupe, can never be 100% accurate.

3) Re performance:

What does this show on one of your media servers:

powercfg -list

findstr "ContentRouter CRDataStore BufferSize" "D:\Program Files\Veritas\pdde\contentrouter.cfg"

fsutil fsinfo ntfsinfo X: | find /i "per cluster"
fsutil behavior query disable8dot3        (i.e. show system default)
fsutil behavior query disable8dot3 X:
fsutil behavior query disablelastaccess
reg query "HKLM\SYSTEM\CurrentControlSet\Control\FileSystem"

reg query "HKLM\SYSTEM\CurrentControlSet\Services\RpcXdr\Parameters"        /v "DefaultNumberofWorkerThreads"
reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Executive" /v "AdditionalDelayedWorkerThreads"
reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Executive" /v "AdditionalCriticalWorkerThreads"

netsh int ipv4 show dynamicportrange udp
netsh int ipv4 show dynamicportrange tcp
netsh int ipv6 show dynamicportrange udp
netsh int ipv6 show dynamicportrange tcp
reg query "HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" /v "MaxUserPort"

reg query "HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" | sort
reg add   "HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" /v "KeepAliveTime"

netsh interface tcp show global
reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters"

You should be able to use the above items in Gogle searches to help get you started along the road of tuning up your Windows based MSDP server.

i.e. readup on the topics surrounding each of the technical elements above.  I can't tell you what to change in your environment.  You have to make reasoned decisions and choices.

Thanks for the comments.

Do you have any suggestion on how to calculate or any NBU tool to check the total maximum backup throughput to a MSDP disk pool?

We need that assessment information of the current existing backup system to support new data growth and new servers.

Again, this a very difficult to calculate.  E.g. if you were to backup only zeroes to an MSDP pool then you would see some ridiculously high transfer rates, and if you were to backup only utterly unique data then the throughput levels would be much lower.

You can use GEN_DATA style backup policies (if you have some Linux/Unix) clients to hand... and use such test backups to see what effect best case, and worst case... levels of sameness/randomness(i.e. uniqueness) have.