It is not common to have SQL log files larger than data files.
If it is, this may indicate a potential problem:
- A possible bad maintenance plan (backups are not being performed correctly).
- There is a process that has a massive size transaction. Or transaction is never commited.
- SQL replication may be broken.
By the way, this check is a part of our SQL Server Health Check service.
How to find databases with Log files larger than database files?
You can use the script below. It will return all databases with logs files (over 1GB) larger than data file.
SELECT
DB_NAME(a.database_id) AS DatabaseName,
CAST((CAST(a.size AS BIGINT) * 8 / 1000000) AS NVARCHAR(20)) AS 'LogFileSize_GB'
FROM sys.master_files a
WHERE a.type = 1
AND DB_NAME(a.database_id) >4
AND a.size > 125000 /* Size is measured in pages here, so this gets us log files over 1GB. */
AND a.size > ( SELECT SUM(CAST(b.size AS BIGINT))
FROM sys.master_files b
WHERE a.database_id = b.database_id
AND b.type = 0)
AND a.database_id IN (
SELECT database_id
FROM sys.databases
WHERE source_database_id IS NULL)
How can I fix the issue?
Read the details below for information on how to:
- Check if you are using the correct recovery model.
- Verify the maintenance plans.
- Shrink the transaction log file.
References:
Microsoft – A transaction log grows unexpectedly or becomes full in SQL Server
Microsoft Manage the size of the transaction log file
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One Response
Hey Jose,
thanks for this script (even though a little buggy…). It helped point out some issues around recovery models and types of backups that were set up and what changes needed to be made.
Cheers!