Determining The Transaction Log Size

How to determine the Transaction Log file size.
Currently the OLTP database (SQL SERVER 2008) takes avg 5 million transaction each day and we have kept in simple recovery mode.We have like 3 month data retention  and the size of rthe db  is around 150G.In next couple of months we will be changing to full recovery mode with 12 month data retention (around 1 terabyte) and also implement transactional  Replication.
The log drive  currently sits on a 250G fibre channel drive.
How much would I need increase the size to fit in the above requirements?
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Great question...but it is kind of guess work.  The reason I say that is because it depends on a few different things:
1.  how often are you going to be doing trans log backups?
2.  are you planning on having any long running transactions

The more often you do log backups, the more often the log is truncated (reused).

One important thing to note is that you want to keep the number of Virtual log files to a minimum..they'll be created when the log file is, set the log file large (maybe 20gb or so to start) and have it grow in large increments.  Doing so will aid in recovery should you ever need to do so.

Here is a list of things that prevent log truncation:
venk_rAuthor Commented:
Thanks for the reply.
We are planning to do the log backups may be evry 2-3 hrs.
And no , not much long running transactions.
Remember we are configuring transaction Replication.

Being said would it ok if I place it in a drive with say 400G in size?
I would imagine that would be fine, yes.  If it starts getting out of hand then I would start doing more frequent log backups.

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venk_rAuthor Commented:
thanks for the reply
venk_rAuthor Commented:
You're welcome, but this was not a B answer.  
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Microsoft SQL Server

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