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What does VLF stand for in transaction log file?
VLF stands for Virtual Log File and the transaction log file is made up of one or more virtual log files.
Why are there too many VLFS in SQL Server?
Too many virtual log files can cause transaction log backups to slow down and can also slow down database recovery, and in extreme cases, even affect insert/update/delete performance. This part of our SQL Server sp_Blitz script checks the number of virtual log files (VLFs) in each database and alerts when there’s 1,000 or more.
What causes high vlf count on index rebuild?
I ran a full index rebuild at the weekend during which the log file swelled to about 32GB on a 46GB data file with 10MB log autogrowth which I imagine has caused the high VLF count. From what I understand I should have upped the autogrowth, however this is not typical activity.
What does VLF stand for in SP _ Blitz?
sp_Blitz Result: High Virtual Log File (VLF) Count. VLF stands for Virtual Log File and the transaction log file is made up of one or more virtual log files. The number of virtual log files can grow based on the autogrowth settings for the log file and how often the active transactions are written to disk.
What happens when you fill a VLF on a second file?
Once you fill up the last VLF on the first file it starts writing to the second file while the first sits idle. If these are on separate drives that means each drive has to be able to handle the I/O, but it’s hit or miss if you’re using the I/O which leads to wasted resources and inconsistent performance.
Is there a way to change the size of VLFS?
There’s only one way to change the size of your VLFs. Delete them and recreate them. For every database EXCEPT TempDB, this means shrinking the logs (it deletes VLFs to get to the size you want), then growing the logs again.
What to do if you have too many VLFS?
So if you have too many VLFs you can shrink your log file. It will delete VLFs that are not in use to make it smaller. Then grow the file in increments that give you VLFs sized how you want them. If you’re going for 500 MB VLFs then you grow your file 8,000 MB at a time.