• How To
• Resize Log File Sql Server

Making a log file smaller should really be reserved for scenarios where it encountered unexpected growth which you do not expect to happen again. If the log file will grow to the same size again, not very much is accomplished by shrinking it temporarily. Now, depending on the recovery goals of your database, these are the actions you should take. First, take a full backup Never make any changes to your database without ensuring you can restore it should something go wrong. If you care about point-in-time recovery (And by point-in-time recovery, I mean you care about being able to restore to anything other than a full or differential backup.) Presumably your database is in FULL recovery mode. If not, then make sure it is: ALTER DATABASE testdb SET RECOVERY FULL; Even if you are taking regular full backups, the log file will grow and grow until you perform a log backup - this is for your protection, not to needlessly eat away at your disk space. You should be performing these log backups quite frequently, according to your recovery objectives.

Shrink log file size. To reduce the physical size of a physical log file, you must shrink the log file. This is useful when you know that a transaction log file contains unused space. You can shrink a log file only while the database is online, and.

For example, if you have a business rule that states you can afford to lose no more than 15 minutes of data in the event of a disaster, you should have a job that backs up the log every 15 minutes. Here is a script that will generate timestamped file names based on the current time (but you can also do this with maintenance plans etc., just don't choose any of the shrink options in maintenance plans, they're awful).

How To

DECLARE @path NVARCHAR(255) = N' backupshare log testdb' + CONVERT(CHAR(8), GETDATE, 112) + ' + REPLACE(CONVERT(CHAR(8), GETDATE, 108),':',') + '.trn'; BACKUP LOG foo TO DISK = @path WITH INIT, COMPRESSION; Note that backupshare should be on a different machine that represents a different underlying storage device. Backing these up to the same machine (or to a different machine that uses the same underlying disks, or a different VM that's on the same physical host) does not really help you, since if the machine blows up, you've lost your database and its backups. Depending on your network infrastructure it may make more sense to backup locally and then transfer them to a different location behind the scenes; in either case, you want to get them off the primary database machine as quickly as possible.

Now, once you have regular log backups running, it should be reasonable to shrink the log file to something more reasonable than whatever it's blown up to now. This does not mean running SHRINKFILE over and over again until the log file is 1 MB - even if you are backing up the log frequently, it still needs to accommodate the sum of any concurrent transactions that can occur. Log file autogrow events are expensive, since SQL Server has to zero out the files (unlike data files when instant file initialization is enabled), and user transactions have to wait while this happens. You want to do this grow-shrink-grow-shrink routine as little as possible, and you certainly don't want to make your users pay for it. Note that you may need to back up the log twice before a shrink is possible (thanks Robert). So, you need to come up with a practical size for your log file. Nobody here can tell you what that is without knowing a lot more about your system, but if you've been frequently shrinking the log file and it has been growing again, a good watermark is probably 10-50% higher than the largest it's been.

Let's say that comes to 200 MB, and you want any subsequent autogrowth events to be 50 MB, then you can adjust the log file size this way: USE master; GO ALTER DATABASE Test1 MODIFY FILE (NAME = yourdblog, SIZE = 200MB, FILEGROWTH = 50MB); GO Note that if the log file is currently 200 MB, you may need to run this first: USE yourdb; GO DBCC SHRINKFILE(yourdblog, 200); GO If you don't care about point-in-time recovery If this is a test database, and you don't care about point-in-time recovery, then you should make sure that your database is in SIMPLE recovery mode. ALTER DATABASE testdb SET RECOVERY SIMPLE; Putting the database in SIMPLE recovery mode will make sure that SQL Server re-uses portions of the log file (essentially phasing out inactive transactions) instead of growing to keep a record of all transactions (like FULL recovery does until you back up the log). CHECKPOINT events will help control the log and make sure that it doesn't need to grow unless you generate a lot of t-log activity between CHECKPOINTs. Next, you should make absolute sure that this log growth was truly due to an abnormal event (say, an annual spring cleaning or rebuilding your biggest indexes), and not due to normal, everyday usage. If you shrink the log file to a ridiculously small size, and SQL Server just has to grow it again to accommodate your normal activity, what did you gain? Were you able to make use of that disk space you freed up only temporarily? If you need an immediate fix, then you can run the following: USE yourdb; GO CHECKPOINT; GO CHECKPOINT; - run twice to ensure file wrap-around GO DBCC SHRINKFILE(yourdblog, 200); - unit is set in MBs GO Otherwise, set an appropriate size and growth rate.

As per the example in the point-in-time recovery case, you can use the same code and logic to determine what file size is appropriate and set reasonable autogrowth parameters. Some things you don't want to do. Back up the log with TRUNCATEONLY option and then SHRINKFILE.

For one, this TRUNCATEONLY option has been deprecated and is no longer available in current versions of SQL Server. Second, if you are in FULL recovery model, this will destroy your log chain and require a new, full backup.

Detach the database, delete the log file, and re-attach. I can't emphasize how dangerous this can be. Your database may not come back up, it may come up as suspect, you may have to revert to a backup (if you have one), etc. Use the 'shrink database' option. DBCC SHRINKDATABASE and the maintenance plan option to do the same are bad ideas, especially if you really only need to resolve a log problem issue.

Target the file you want to adjust and adjust it independently, using DBCC SHRINKFILE or ALTER DATABASE. MODIFY FILE (examples above). Shrink the log file to 1 MB. This looks tempting because, hey, SQL Server will let me do it in certain scenarios, and look at all the space it frees! Unless your database is read only (and it is, you should mark it as such using ALTER DATABASE), this will absolutely just lead to many unnecessary growth events, as the log has to accommodate current transactions regardless of the recovery model. What is the point of freeing up that space temporarily, just so SQL Server can take it back slowly and painfully?.

Create a second log file. This will provide temporarily relief for the drive that has filled your disk, but this is like trying to fix a punctured lung with a band-aid. You should deal with the problematic log file directly instead of just adding another potential problem.

Other than redirecting some transaction log activity to a different drive, a second log file really does nothing for you (unlike a second data file), since only one of the files can ever be used at a time. Be proactive Instead of shrinking your log file to some small amount and letting it constantly autogrow at a small rate on its own, set it to some reasonably large size (one that will accommodate the sum of your largest set of concurrent transactions) and set a reasonable autogrow setting as a fallback, so that it doesn't have to grow multiple times to satisfy single transactions and so that it will be relatively rare for it to ever have to grow during normal business operations. The worst possible settings here are 1 MB growth or 10% growth. Funny enough, these are the defaults for SQL Server (which I've complained about and ) - 1 MB for data files, and 10% for log files.

The former is much too small in this day and age, and the latter leads to longer and longer events every time (say, your log file is 500 MB, first growth is 50 MB, next growth is 55 MB, next growth is 60.5 MB, etc. and on slow I/O, believe me, you will really notice this curve). Further reading Please don't stop here; while much of the advice you see out there about shrinking log files is inherently bad and even potentially disastrous, there are some people who care more about data integrity than freeing up disk space. I would also want to add that clearing the log is done by backing up the log (in full or bulk-logged recovery) or a checkpoint (in simple recovery). However, if you are in a situation where you must shrink the log file, that's not enough. You need to cause the currently active VLF to cycle back to the start of the log file.

Resize Log File Sql Server

You can force this in SQL 2008 and newer by issuing two log backups or checkpoints back-to-back. The first one clears it and the second one cycles it back to the start of the file. – Aug 17 '13 at 19:26. DISCLAIMER: Please read comments below carefully, and I assume you've already read the accepted answer. As I said nearly 5 years ago: if anyone has any comments to add for situations when this is NOT an adequate or optimal solution then please comment below. Right click on the database name. Select Tasks → Shrink → Database.

Then click OK! I usually open the Windows Explorer directory containing the database files, so I can immediately see the effect. I was actually quite surprised this worked! Normally I've used DBCC before, but I just tried that and it didn't shrink anything, so I tried the GUI (2005) and it worked great - freeing up 17 GB in 10 seconds In Full recovery mode this might not work, so you have to either back up the log first, or change to Simple recovery, then shrink the file. thanks @onupdatecascade for this - PS: I appreciate what some have commented regarding the dangers of this, but in my environment I didn't have any issues doing this myself especially since I always do a full backup first. So please take into consideration what your environment is, and how this affects your backup strategy and job security before continuing.

All I was doing was pointing people to a feature provided by Microsoft! Here is an exaggeration to demonstrate what is happening and why shrinking is absolutely critical on a periodic basis: Record A is changed 1 million times before a backup is done.

What is in the log? 999,999 pieces of data that are irrelevant. If the logs are never shrunk you will never know what the true operating expense of the database is. Also, you are hogging valuable resources on a SAN, most likely. Shrinking is good maintenance and keeps you in touch with your environment. Show me someone who thinks you should never shrink and I'll show you someone ignoring their environment.

– Feb 10 '15 at 19:37. Below is a script to shrink the transaction log, but I’d definitely recommend backing up the transaction log before shrinking it.

If you just shrink the file you are going to lose a ton of data that may come as a life saver in case of disaster. The transaction log contains a lot of useful data that can be read using a third-party transaction log reader (it can be read manually but with extreme effort though). The transaction log is also a must when it comes to point in time recovery, so don’t just throw it away, but make sure you back it up beforehand. Here are several posts where people used data stored in the transaction log to accomplish recovery:. USE DATABASENAME; GO ALTER DATABASE DATABASENAME SET RECOVERY SIMPLE; GO -First parameter is log file name and second is size in MB DBCC SHRINKFILE (DATABASENAMELog, 1); ALTER DATABASE DATABASENAME SET RECOVERY FULL; GO You may get an error that looks like this when the executing commands above “Cannot shrink log file (log file name) because the logical log file located at the end of the file is in use“ This means that TLOG is in use.

In this case try executing this several times in a row or find a way to reduce database activities. ' Simple.and never fill up again' - not true. I've seen it happen (in the past 48 hours) on a database where the Recovery Model was set to 'SIMPLE'. The logfile's filegrowth was set to 'restricted', and we'd been doing some immense activity on it. I understand that it was an unusual situation. (In our situation, where we had plenty of disc space, we increased the logfile size, and set logfile filegrowth to 'unrestricted'.

Which by the way -interface bug- shows up, after the change, as 'restricted' with a maxsize of 2,097,152 MB.) – Dec 10 '13 at 18:10. Most answers here so far are assuming you do not actually need the Transaction Log file, however if your database is using the FULL recovery model, and you want to keep your backups in case you need to restore the database, then do not truncate or delete the log file the way many of these answers suggest.

Eliminating the log file (through truncating it, discarding it, erasing it, etc) will break your backup chain, and will prevent you from restoring to any point in time since your last full, differential, or transaction log backup, until the next full or differential backup is made. From the We recommend that you never use NOLOG or TRUNCATEONLY to manually truncate the transaction log, because this breaks the log chain.

Until the next full or differential database backup, the database is not protected from media failure. Use manual log truncation in only very special circumstances, and create backups of the data immediately. To avoid that, backup your log file to disk before shrinking it. The syntax would look something like this: BACKUP LOG MyDatabaseName TO DISK='C: DatabaseBackups MyDatabaseNamebackup2013.trn' DBCC SHRINKFILE (N'MyDatabaseNameLog', 200).

The SQL Server transaction log needs to be properly maintained in order to prevent its unwanted growth. This means running transaction log backups often enough. By not doing that, you risk the transaction log to become full and start to grow. Besides the answers for this question I recommend reading and understanding the transaction log common myths. These readings may help understanding the transaction log and deciding what techniques to use to 'clear' it: From: Myth: My SQL Server is too busy. I don’t want to make SQL Server transaction log backups One of the biggest performance intensive operations in SQL Server is an auto-grow event of the online transaction log file.

By not making transaction log backups often enough, the online transaction log will become full and will have to grow. The default growth size is 10%.

The busier the database is, the quicker the online transaction log will grow if transaction log backups are not created Creating a SQL Server transaction log backup doesn’t block the online transaction log, but an auto-growth event does. It can block all activity in the online transaction log From: Myth: Regular log shrinking is a good maintenance practice FALSE. Log growth is very expensive because the new chunk must be zeroed-out. All write activity stops on that database until zeroing is finished, and if your disk write is slow or autogrowth size is big, that pause can be huge and users will notice. That’s one reason why you want to avoid growth. If you shrink the log, it will grow again and you are just wasting disk operation on needless shrink-and-grow-again game.

If the transaction log file (.ldf) in Microsoft SQL Server is too big, it can cause performance issues, eat up valuable disk space and consume resources when a back up is performed, therefore it's imperative to periodically maintain the database to keep the.ldf file under control. To reduce the.ldf file, you must do three things:. Backup the database. Stop the database service. Shrink the.ldf file SQL Management Studio offers a simple GUI to perform both those tasks.

If you are not sure how big your database's.ldf file is, SQL Management studio will let you see this information. To preview and reduce your SQL database.ldf file, follow these directions: Open SQL management Studio and find your database. Right click on it and select properties. From the left hand pane, select Files. The image above shows a 5GB database with a 49 GB.ldf transaction log.

Click OK to exit the window. Right click on your database and select Tasks Backup Make sure the backup type is Full and select a destination. Click OK to proceed. Once the backup has completed, stop the SQL server service, then right click on the database and select Tasks Shrink Shrink Files. Select Log as the file type and select Release unused space.

Click OK, to proceed. This will truncate the log file.