Disk space needed for a recover NAV backup (transaction log)

mr_ash

It is possible to estimate how much transaction log will grow up in time of recovering database from NAV backup (not SQL) ? I must recover 100GB (data not files) database and I don't know how big hdd should I use for a transaction log file. In normal conditions size of the log file don't exceed 10GB.
I hope someone of you has an experience with case like this.
Thanks in advance!

DenSter

It really depends on the table design and how many keys are enabled on SQL Server. It usually is about 1.5-2 times the database size, but I would make sure you have room for 3 times the size. I'm talking about the database size of the original database, not the size of the backup file. So if your original database size is 100GB then I would make sure I have 300GB of space for the transaction log.

What would be much easier is to take a SQL Server backup, that is basically a copy of the data files. That way you know exactly what size you need.

bbrown

A SQL backup will recreate the database files then same size as the original database from which it was created. The SQL backup retains enough information to effectively recreate those files. Let's say you have a 100 GB database with 25 GB of data. The backup will be about 25 GB (the data) plus the active portion of the log. The restore will recreate the original database of 100 GB.

If you have a SQL backup you can use the following T-SQL command to find out how large the restored files will be. Along with other information such as the default paths and names.

RESTORE FILELISTONLY 
   FROM DISK = 'R:\backup\MyBackup.bak'

mr_ash

Thanks for the responses!

And yes... but SQL backup is not a problem. The worst thing is that I must perform NAV backup/restore operation. Operation like this, on so big database is very time consuming, and I'll don't have time for mistakes (like not enought disk space)

bbrown

Why must you use NAV backup?