Comments on: A Busy/Accidental DBA’s Guide to Managing VLFs http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/ Random thoughts, rants, discoveries and things I wish I had done better Tue, 17 Apr 2012 18:47:04 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: David Levy http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-8345 David Levy Tue, 13 Mar 2012 14:06:53 +0000 http://adventuresinsql.com/?p=12#comment-8345 I have never seen it break the log chain. Can you share more details like SQL version, steps you took before and after, recovery model, etc.? I have never seen it break the log chain. Can you share more details like SQL version, steps you took before and after, recovery model, etc.?

]]> By: Dave Plung http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-8341 Dave Plung Tue, 13 Mar 2012 11:45:38 +0000 http://adventuresinsql.com/?p=12#comment-8341 Just testet it out...it DOES affect the Backup Chain. So before you run this script take a Full Backup before and after you ran the script. Just testet it out…it DOES affect the Backup Chain. So before you run this script take a Full Backup before and after you ran the script.

]]> By: Dave Plung http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-8336 Dave Plung Tue, 13 Mar 2012 07:40:36 +0000 http://adventuresinsql.com/?p=12#comment-8336 Does this script affect the Backup Chain ? Does this script affect the Backup Chain ?

]]> By: DBA Darwin Awards: Log File Edition | Brent Ozar PLF | Brent Ozar PLF http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-7430 DBA Darwin Awards: Log File Edition | Brent Ozar PLF | Brent Ozar PLF Tue, 24 Jan 2012 12:30:21 +0000 http://adventuresinsql.com/?p=12#comment-7430 [...] A Busy/Accidental DBA’s Guide to Managing VLFs – Dave Levy explains the basics of Virtual Log Files, gives you a script to check how many you’ve got, and shows how to fix the problem. [...] [...] A Busy/Accidental DBA’s Guide to Managing VLFs – Dave Levy explains the basics of Virtual Log Files, gives you a script to check how many you’ve got, and shows how to fix the problem. [...]

]]> By: Ali Razeghi http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-2608 Ali Razeghi Wed, 13 Apr 2011 04:17:23 +0000 http://adventuresinsql.com/?p=12#comment-2608 Yoo David, Nice post on VLFs to accidental DBAs! I've been thinking a lot about that and started my own blog on the subject but focusing on different parts. I like the way you presented VLFs and will link to your blog when I'm explaining why and how they need to maintain indexes. Good stuff. Yoo David,
Nice post on VLFs to accidental DBAs! I’ve been thinking a lot about that and started my own blog on the subject but focusing on different parts. I like the way you presented VLFs and will link to your blog when I’m explaining why and how they need to maintain indexes. Good stuff.

]]> By: David Levy http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-760 David Levy Sat, 20 Nov 2010 03:58:44 +0000 http://adventuresinsql.com/?p=12#comment-760 Wow! That is a great catch. Nicely done! I have never run into that because I cheat and use 1000MB as 1GB to make it easy to calculate max size in my head. I will have to remember that when I finally switch over to using GB. The one thing I want to call out is that 10 GB seems sort of big for an autogrowth increment. I would keep an eye out for performance issues if the log has to grow. I hardly ever go over 1000MB for autogrowth of either type of file. Wow! That is a great catch. Nicely done!

I have never run into that because I cheat and use 1000MB as 1GB to make it easy to calculate max size in my head. I will have to remember that when I finally switch over to using GB.

The one thing I want to call out is that 10 GB seems sort of big for an autogrowth increment. I would keep an eye out for performance issues if the log has to grow. I hardly ever go over 1000MB for autogrowth of either type of file.

]]> By: Oleg http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-759 Oleg Sat, 20 Nov 2010 03:44:54 +0000 http://adventuresinsql.com/?p=12#comment-759 Too many VLF was due to SQL bug. http://www.sqlskills.com/BLOGS/PAUL/post/Bug-log-file-growth-broken-for-multiples-of-4GB.aspx I changed autogrowth to 10GB Too many VLF was due to SQL bug. http://www.sqlskills.com/BLOGS/PAUL/post/Bug-log-file-growth-broken-for-multiples-of-4GB.aspx I changed autogrowth to 10GB

]]> By: David Levy http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-756 David Levy Fri, 19 Nov 2010 23:23:09 +0000 http://adventuresinsql.com/?p=12#comment-756 I can't make the math work for the situation you are seeing. To grow 300GB in 8 GB you should get 16 VLFs per growth so (300/8)*16=~600 VLFs. Based on my calculations your average autogrowth is around 178MB. Are you sure there is not something else going on? I would suggest running a checkdb on the database and checking for any unusual configuration settings. Also, talk to coworkers to see if anyone else is doing any special maintenance. I can’t make the math work for the situation you are seeing. To grow 300GB in 8 GB you should get 16 VLFs per growth so (300/8)*16=~600 VLFs. Based on my calculations your average autogrowth is around 178MB.

Are you sure there is not something else going on? I would suggest running a checkdb on the database and checking for any unusual configuration settings. Also, talk to coworkers to see if anyone else is doing any special maintenance.

]]> By: Oleg http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-755 Oleg Fri, 19 Nov 2010 22:53:43 +0000 http://adventuresinsql.com/?p=12#comment-755 Hi Dave, We had 1,500,000 VLFs in it. I shrinked the log and pregrow it to 400GB. Week later it autogrow to 700GB in 8GB steps and we are in the same situation – 1,000,000 VLFs. During the week we loaded 300Gb data and backed up readwrite filegroup (5 days). I wonder what caused so many VLFs and how to prevent it from happening. Make 1TB log next time? Oleg Hi Dave,

We had 1,500,000 VLFs in it. I shrinked the log and pregrow it to 400GB. Week later it autogrow to 700GB in 8GB steps and we are in the same situation – 1,000,000 VLFs. During the week we loaded 300Gb data and backed up readwrite filegroup (5 days). I wonder what caused so many VLFs and how to prevent it from happening. Make 1TB log next time?

Oleg

]]> By: David Levy http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-752 David Levy Fri, 19 Nov 2010 15:42:19 +0000 http://adventuresinsql.com/?p=12#comment-752 Yikes! I wonder how long that code has been broken. I fixed it now. Thanks for pointing that out! Yikes!

I wonder how long that code has been broken. I fixed it now.

Thanks for pointing that out!

]]> By: Jonathan Gardner http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-751 Jonathan Gardner Fri, 19 Nov 2010 15:30:14 +0000 http://adventuresinsql.com/?p=12#comment-751 I think you have some issues with the code. I just tried to run the first it and line 21 and 57. You will see a &LT; and >. Those are typically issues with the way the <code> functions work. You may want to correct them and offer the code in a downlad file as well. That aside, great article. I have been needing to take a look a this and your code will be a great start. Thank you. I think you have some issues with the code. I just tried to run the first it and line 21 and 57. You will see a &LT; and >. Those are typically issues with the way the functions work. You may want to correct them and offer the code in a downlad file as well.

That aside, great article. I have been needing to take a look a this and your code will be a great start. Thank you.

]]> By: Want to Make Your SQL Server Run Faster for Free? | Adventures in SQL http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-743 Want to Make Your SQL Server Run Faster for Free? | Adventures in SQL Fri, 19 Nov 2010 03:24:20 +0000 http://adventuresinsql.com/?p=12#comment-743 [...] doing that? Great question. There are lots of great posts out there on how to do this. Here is an article that I wrote detailing the process that I use and some of the reasoning behind [...] [...] doing that? Great question. There are lots of great posts out there on how to do this. Here is an article that I wrote detailing the process that I use and some of the reasoning behind [...]

]]> By: David Levy http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-365 David Levy Tue, 14 Sep 2010 20:44:07 +0000 http://adventuresinsql.com/?p=12#comment-365 That is a great catch! I used to set the auto growth higher but have stopped because it was causing my auto growth settings to go too high. It turned out that the growth setting I had really did not matter as much when the logs were well maintained because they very rarely grow. If you are constantly seeing high VLF numbers there is usually another problem like someone shrinking the files, autoshrink being turned, unexpected data growth or any other issue that really should be addressed. That is a great catch! I used to set the auto growth higher but have stopped because it was causing my auto growth settings to go too high. It turned out that the growth setting I had really did not matter as much when the logs were well maintained because they very rarely grow. If you are constantly seeing high VLF numbers there is usually another problem like someone shrinking the files, autoshrink being turned, unexpected data growth or any other issue that really should be addressed.

]]> By: Calvin Jones http://adventuresinsql.com/2009/12/a-busyaccidental-dbas-guide-to-managing-vlfs/comment-page-1/#comment-364 Calvin Jones Tue, 14 Sep 2010 20:34:45 +0000 http://adventuresinsql.com/?p=12#comment-364 You calculate a value for @file_growth but don't use it. Should it be part of the ALTER DATABASE statement to re-grow the transaction log? You calculate a value for @file_growth but don’t use it. Should it be part of the ALTER DATABASE statement to re-grow the transaction log?

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