1) Is it feasible to export 400gb database?

400Gb is practically too big for an export.

2) What will be the size of export dump file?

ummm 400Gb??

3) Will it affect by unix file size limit?

yes

4) What long will it take .guess only on normal basis as it depends on lot of parameters. I agree.

hours and hours (days?)

5) How long will it take to ftp? only guess

depends how quick your network is

6) What are the parameters need to consider for import on test seerver?

if you got a spare few days to wait

7) What is raw device?can we use it for export or import?

if you dont know what a raw device, you dont want to know

8) Same size database restore on new test server with backup? how long will it take for ftp and restore and database availability time.

how long is a piece of string?


heres a better idea for you. If it is the same OS on the other server (which I assume it is due to it being a test server) then shutdown your database, copy all the database files to your new server, backup the control file to trace then recreate the database from there - no export and no import and a whole lot of saved time