Splitting up a large MDF file

I wanted to break-up a single 500GB MDF file into 5 files of around 100GB each, so created 4 NDF files.

I set autogrowth to 1024 MB for the NDF files and OFF for the MDF file.

In a SQL Job I used code like …


Which after the second weekend left about 88GB in the MDF file.


select Physical_Name,
	ROUND(CAST((size) AS FLOAT)/128,2) Size_MB,
	ROUND(CAST((FILEPROPERTY([name],'SpaceUsed')) AS FLOAT)/128,2) Used_MB,
	convert(int, ROUND(CAST((FILEPROPERTY([name],'SpaceUsed')) AS float)/128,2) / ROUND(CAST((size) AS float)/128,2) * 100) Used_Pct
FROM sys.database_files
where physical_name not like '%ldf%'
order by physical_name;

I cancelled and deleted the job.

Over the next 3 week nights I reduced its physical size to 300GB, 200GB, then 100GB using a Job step like …

DBCC SHRINKFILE (N'MDFLogicalFileName', 100000);

I set MDF autogrowth to match the NDF files, so the five would naturally balance (size wise) over time.

Lastly I set up a nightly job to rebuild the most fragmented indexes (Thanks again Ola).

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s