This is almost the exact scenario I have. However, I need to ask these 
questions:

How is the data moving? I use Fiber Channel to connect from the server to the 
Data Domain and DD to SL8500. How the data moves will impact how many media 
servers you need.

How fast do you need the data moved? If you have the luxury of time you can use 
less media servers. I am running DD990 and I am getting 3200MB/Sec in and out 
to tape (roughly 16X100MB in and out) since I duplicate to tape using SLP while 
I am running backups.

How is the data stored/accessed? Mine is mostly in Oracle Databases. Each of my 
Oracle DB ( mine are 9 - 40TB each ) has its own media server to send the data 
to the Data Domains. So I have a master and 5 media servers. BUT - these are 
clusters of Solaris so most of my DB have 2 or 3 servers they could be on, so 
those 5 media servers are actually 10 media servers with 5 active at any one 
time, AND I have TEST/QA and DR media servers, so I end up with 24 media 
servers - can you say site license?

Since I use Fiber Channel we started with two DD990 so that we would have 
enough FC HBA to generate the throughput to drive the LTO5 tape drives. We 
ended up getting another DD7200 recently to handle growth.  Please note - due 
to the DD deduplication, you have to have a process that labels or formats the 
DD tapes as they go to scratch, or it does not release the disk space. The 
cleaning process has a definite impact on throughput as well.

----------------------------------------------------------------------

Message: 1
Date: Tue, 09 Dec 2014 01:29:55 -0800
From: sonsofjorge <nbu-forum AT backupcentral DOT com>
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Subject: [Veritas-bu]  Media Servers needed
Message-ID: <1418117395.m2f.400716 AT www.backupcentral DOT com>

Quick ball park numbers only.

Can anyone have estimates on how many media servers do I need to support a 
360TB data.   I am looking at using high end Data Domain as deduplication 
device and Oracle SL8500 for tape out.


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