The process of getting a database from FDB to SQL is a bit more involved than simply doing an FBK restore. The way that dates and code fields are stored is different between the two, and there almost always has to be data cleanup in the FDB prior to doing the restore. The out of memory error doesn't mean that the server ran out of memory; it means that the FINSQL.exe process ran out of its own memory, and since that is a 32 bit application, it can only reference 2GB of ram. My experience is that you get that error because of data problems, not because of server hardware resources.
Also be aware that you cannot just do an FBK restore from an older version into 2013 or newer because the data is now stored in UNICODE, so your best bet (until you are ready to do an actual NAV upgrade including objects) is to target 2009R2 with the latest update rollup. Don't think about 2013 or newer until you get this onto SQL in 2009R2.
Other caveats - there may be some object changes (code changes) that also have to be done, as some behaviours are different for table locking. You'll want a lot of user testing prior to going live to reveal code problems.
I'll do a little research to see if I can find the conversion instructions from Microsoft. But for planning purposes, your steps will look something like this (I am greatly simplifying here):
Copy the FDB from last night's Hotcopy (you are using hotcopy for backups every night, yes?) to your new SQL server
Open that FDB with 2009R2 classic client fin.exe - this will convert the data from 3.7 to 2009R2 on the SQL server
Run the data examination steps from the Upgrade Toolkit for 2009R2
This step examines code and date fields
Correct the data problems
Test the whole integrity of the database
Correct any key problems from the integrity tests
Create a new FBK from this cleansed FDB
Restore FBK with finsql.exe onto SQL server
Have users test extensively - chart of accounts is sorted correctly, accounting schedules work, etc
Repeat these steps for your go-live (did I mention the extensive user testing)?
For a 70G database, I'd allow a full day for the above process, though the time is very dependent on how many data problems exist, and how beefy your SQL server hardware is.
But don't go live with SQL until everyone has signed off that testing has been successful.
Kyle Hardin
Developer and SQL Wrangler
ArcherPoint