Lazy Log Truncation

Paul Randal explains why Virtual Log Files might remain in status 2 even after they are cleared:

Earlier this year I was sent an interesting question about why the person was seeing lots of VLFs in the log with status = 2 (which means ‘active’) after clearing (also known as ‘truncating’) the log and log_reuse_wait_desc showed NOTHING.

I did some digging around and all I could find was an old blog post from 2013 that shows the behavior and mentions that this happens with mirroring and Availability Groups. I hadn’t heard of this behavior before but I guessed at the reason, and confirmed with the SQL Server team.

Read on for the answer.

Related Posts

Workarounds for Updating Stats on Secondaries

Niko Neugebauer wants statistics updates on tables running on readable Availability Group secondary nodes: Let’s list the basic known details for the possible solution(for the Enterprise Edition of the Sql Server that is):– We can make the secondary replica readable and read the same data on it. (Not that you should do that by default, […]

Read More

Dealing with HADR_SYNC_COMMIT Waits

Dmitri Korokevitch walks us through the HADR_SYNC_COMMIT wait type: The secondary nodes may be configured using asynchronous or synchronous commit. With asynchronous commit, transaction considered to be committed and all locks were released when COMMIT log record is hardened on the primary node. SQL Server sends COMMIT record to secondary node; however, it does not […]

Read More

Categories

October 2018
MTWTFSS
« Sep Nov »
1234567
891011121314
15161718192021
22232425262728
293031