How long does it take to copy the data?

The question often arises as to how long the data can be migrated. Let's calculate with an example. Initial data:
 

• new server with 1 Gbit/s channel
• old server with 100 Mbit/s channel
• data to be transferred - 1 TB

 
Let's convert 1 TB to MB:
1 TB * 1024 = 1 024 GB
1 024 GB * 1024 = 1 048 576 MB
 
Let's convert MB to Mbit:
1,048,576 MB * 8 = 8,388,608 Mbit
 
Let's calculate the time required for the transfer:
8,388,608 Mbit / 100 Mbit/s = 83,886 sec
83 886 sec / 60 = 1 398 min
1 398 min / 60 = 23 hours
 
That is about 24 hours.
 
But you should realize that this is in ideal conditions. And in reality the time will increase depending on:
 

• busy channel on the sending server
• connectivity between servers
• disk load on the sending server
• number of small files