Hi, on my WSUS server, the DB disk is continuously filling up, even when the WSUS service is at 0% CPU use and no network trafic. Is there a reason ?

Question

Hi, on my WSUS server, the DB disk is continuously filling up, even when the WSUS service is at 0% CPU use and no network trafic. Is there a reason ?

Daro, Willy 21

It fills the disk more than 2TB

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Answer accepted by question author

Adam J. Marshall 11,031 MVP

Are you performing the proper WSUS maintenance including but not limited to running the Server Cleanup Wizard (SCW), declining superseded updates, running the SQL Indexing script, etc.?

https://www.ajtek.ca/wsus/how-to-setup-manage-and-maintain-wsus-part-8-wsus-server-maintenance/

Do you have auto-approvals turned on? Look at your sync history - did a large number of updates come in recently?

Abdullah Al Mehedy 0 Reputation points

2026-11-12T15:38:23.9666667+00:00

Hi Adam,
Is it normal to have 300GB of WSUS server getting full even after increase to 400 GB datastore?
Adam J. Marshall 11,031 Reputation points MVP

2026-11-12T16:09:43.9566667+00:00

Generally, no. It depends on if you're performing the required maintenance, and what you have within your network and how many updates are approved. I've usually stayed below 150GB for the past 8 years in total usage. We have clients that have 300-500GB stores (down from 1.7TB), and clients that have less than 50GB in their data store. I'd say generally between 100-300GB is used, but all depending on what your network has and how you manage your WSUS server (approving updates - automatic vs approving only NEEDED updates like our new software AJ Tek Approvals does), along with what maintenance you're doing (if you're using WAM, you're covered there).

5 additional answers

Your answer

Abdullah Al Mehedy 0 Reputation points

2026-11-12T15:38:23.9666667+00:00

Hi Adam,
Is it normal to have 300GB of WSUS server getting full even after increase to 400 GB datastore?
Adam J. Marshall 11,031 Reputation points MVP

2026-11-12T16:09:43.9566667+00:00

Generally, no. It depends on if you're performing the required maintenance, and what you have within your network and how many updates are approved. I've usually stayed below 150GB for the past 8 years in total usage. We have clients that have 300-500GB stores (down from 1.7TB), and clients that have less than 50GB in their data store. I'd say generally between 100-300GB is used, but all depending on what your network has and how you manage your WSUS server (approving updates - automatic vs approving only NEEDED updates like our new software AJ Tek Approvals does), along with what maintenance you're doing (if you're using WAM, you're covered there).

Answer 1

First investigate: Connect to the SQL Server (https://www.ajtek.ca/wsus/how-do-i-connect-to-the-windows-internal-database-wid/) and run the following SQL Script.

USE SUSDB  
CREATE TABLE #temp (  
table_name sysname ,  
row_count INT,  
reserved_size VARCHAR(50),  
data_size VARCHAR(50),  
index_size VARCHAR(50),  
unused_size VARCHAR(50))  
SET NOCOUNT ON  
INSERT #temp  
EXEC sp_msforeachtable 'sp_spaceused ''?'''  
SELECT a.table_name,  
a.row_count,  
COUNT(*) AS col_count,  
a.data_size  
FROM #temp a  
INNER JOIN information_schema.columns b  
ON a.table_name collate database_default  
= b.table_name collate database_default  
GROUP BY a.table_name, a.row_count, a.data_size  
ORDER BY CAST(REPLACE(a.data_size, ' KB', '') AS integer) DESC  
DROP TABLE #temp

This will give you the output of what tables are taking up the most space. If the top table is tbEventInstance, it's safe to truncate it (empty the data inside that table).

USE SUSDB;
TRUNCATE TABLE tbEventInstance;

Your database can now be shrunk manually.

Answer 2

Daro, Willy 21

And still no CPU use and no network trafic

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Answer 3

Daro, Willy 21

Hi Adam, Shrinking is not the question, the problem is that the DB inflate all the time and I have to expand the drive. This morning, within about 6 hours it fills more than 300GB, at this rate, I will have to expand the drive to 5TB tomorrow.

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Answer 4

Adam J. Marshall 11,031 MVP

The database itself doesn't automatically shrink. This is a fundamental function of SQL. We are actually building a database shrink feature for the next version of WAM, but you can contact our support department for some direct instructions to shrink the database in the meantime, using SQL Management Studio.

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