I am trying to shrink log file in SQL Server to save storage space but instead of decreasing the file size has been increased with a large volume.
I have tried this twice, both of the time file size was increased.
From what you have provided, it seems as if you ran DBCC SHRINKFILE on the log file, and it did not shrink. This is likely due to there not being any free space to actually shrink. What you want to do instead is BACKUP the log file, which will free up space, and allow you to shrink the log file back to your specified size. Afterwards, you probably want to schedule these backups based on your RPO and RTO, which it sounds like you don't have so I'd figure out what that is first.
Since it seems like your log file is growing pretty consistently, I'd assume you are in FULL or BULK LOGGED RECOVERY mode. Regardless, you'll have to conduct a FULL BACKUP before you can do a LOG BACKUP.
If this happens to be TEMPDB, clearing the cache can help.
Related
I am a newbie in SQL Server, I have a task to move the whole SQL Server to another.
I am trying to estimate how much space I need in the new SQL Server.
I ran EXEC sp_spaceused
And the following came up:
When I look into the output, it seems that the Database is using ~122GB (reserved), but when looking in the total database size (mdf + ldf) it is ~1.8 TB.
Does that mean when I copy the Database from the existing SQL Server to a new one I will need ~1.8 TBs into the new?
I am thinking about creating a back-up and copy the back-up to the new Server. How does the back-up takes into consideration the unallocated space? Does the back gets closer to the reserved or the database_size? I understand that this is without taking into consideration the uncompressed in the back-up, which will improve the file size.
Thx for the help.
The backup file will be much smaller than 1.8TB, since unallocated pages are not backed up. But the log and data files themselves will be restored to an identical size, so you will need 1.8TB on the target in order to restore the database in its current state.
Did you check to see if your log file is large due to some uncontrolled growth that happened at some point and is maybe no longer necessary? If this is where all your size is, it's quite possible you can fix this before the move. Make sure you have a full backup and take at least one log backup, then use DBCC SHRINKFILE to bring the log file back into the right stratosphere, especially if it was caused by either a one-time abnormal event or a prolonged log backup neglect that has now been addressed.
I really don't recommend copying/moving the mdf/ldf files (background) or using the SSMS UI to "do a copy" since you can have much greater control over what you're actually doing by using proper BACKUP DATABASE and RESTORE DATABASE commands.
How do I verify how much of the log data is being used?
If you're taking regular log backups (or are in simple recovery), it should usually be a very small % of the file. DBCC SQLPERF(LogSpace); will tell you % in use for all log files.
To minimize the size that the log will require in the backup file itself, then:
if full recovery, back up the log first.
if simple recovery, run a couple of CHECKPOINT; commands first.
I work for an organization and i have come across a problem where i cannot shrink the log file.
The SQL server database is consuming 400 GB out of 600 GB hard disk drive.
The log file size is around 350 GB.
I tried shrinking the log file but the size remains the same.
The recovery model of my database is SIMPLE.
I have gone through online posts where there are suggestions to take backup of the log file and then try shrinking.But I do not have enough free space on my drive to save the log backup.(Note: I have only one drive in my system and I am not supposed to take backup on external drive ).
Will moving this entire DB to a different drive help ?
Any solutions ?
You have an open transaction. Kill all connections then try again.
I tried shrinking the log file but the size remains the same. The
recovery model of my database is SIMPLE.
I have gone through online posts where there are suggestions to take
backup of the log file and then try shrinking.
If your db is in SIMPLE you cannot do log backups.
Instead, you should issue one or more times:
CHECKPOINT; DBCC SHRINKFILE...
This will help in case when log_reuse_wait_desc shows NOTHING/CHECKPOINT.
If it shows anything else you should eliminate the cause of what it's showing on
If your database is in SIMPLE mode, change the file size for the log to a smaller value, as low as 1 MB. The server will size it as small as it can.
However, be aware that the log file is sized to contain all active transactions. In your example, at one point in time you had 350GB worth of transactions in progress. Note that existing server activity can prevent it from shrinking to the desired size.
In simple mode, shrinking the log file is only worthwhile if you had a run-away transaction blow out the log. Otherwise, shrinking the log file doesn't solve anything and impacts performance because the server has to immediately grow the log file again for new transactions.
You can, and should, move the log file to a different drive than the database file.
I tried to shrink the log file but it only did small amount of free space.
The log space of tempdb is full due to the data file.
How can I free the space?
Edit:
I have checked following:
1. Bad queries are running - NO Queries are running
DBCC OPENTRAN - No Result
The tempdb is in SIMPLE recovery mode.
I have a separate drive for Transaction log of 1TB i.e. 40% free now.
Observation:
When I Right click on tempdb>task>shrink>database shows 99% free space available. Can I shrink the database file here?
Restarting the SQL instance will flush the tempdb and recreate it.
I am adding some 2m record in a table with database in Full Recovery but my log file size is not increasing from the default assigned when database was created.What can be the possible reason?
One of two things is happening (possibly both):
The log file is already sized to be sufficient for the activity that you're putting against it.
There are periodic transaction log backups running.
Log size doesn't increase just because there has been a transaction. It increases because the current log file doesn't have enough free space for the transaction.
In other words, 2-million-row transaction is small enough, and with your backup schedule, the system sees no need to increase the physical log file size.
Why this happens is due to backup. When a log backup is taken, the log is truncated. This doesn't mean that the log file will be shrunk. Rather, the unused space will be freed for future transaction while the physical size remain unchanged. This is useful because excessive and repeated increase would take up the system resource unnecessarily. In other words, if your log file is, say 500MB, then it's likely that that's how much space your database typically needs. So shrinking it to 1 MB only have it quickly grown to 500 MB would be likely to affect performance negatively.
To see this in action, observe the log file information by running DBCC SQLPERF(Logspace) in the database you are interested in. INSERT and BACKUP LOG will change the number(s).
Further reading:
Log Truncation
Log Size Management
We are using SQL Server 2008 with full recovery model, the database size is 10 GB and the log file is 172 GB, we want to clear up the space of the log file internally ,we did transaction log file backup it should be clear up, but it still 172 GB ,what to do?
shrink the DB after doing the following task :
/*Perform a full backup of your database.
Change the backup method of your database to "Simple"
Open a query window and enter "checkpoint" and execute
Perform another backup of the database
Perform a final full backup of the database.*/
To understand this, you need to understand the difference between file shrinkage and truncation.
Shrinking means physically shrinking the size of the file on disk. Truncation means logically freeing up space to be used by new data, but with NO impact on the size of the file on disk.
In layman's terms for instance, if your log file is 100 GB in size and you've never backed it up, 100GB of that size is USED. If you then back up the log / database, it will be truncated, meaning the 100GB will be reserved for future use... basically meaning it's freed up for SQL Server, but still uses up the same space on disk as before. You can actually see this with the following query for instance.
DBCC SQLPERF(logspace) WITH NO_INFOMSGS
The result will show on a DB basis how large the log file is, and how much of the log file is actually used. If you now shrink that file, it will free up the reserved portion of the file on disk.
This same logic applies to all files in SQL Server (including primary and partition files, as well as log files for tempdb, user databases etc), even on table-level. For instance if you run this code
sp_spaceused 'myTableName'
You will see how much of that table is reserved and used for various things, where the "unused" column will show how much is reserved but NOT used.
So as a conclusion, you can NOT free up space on disk without shrinking it. The real question here is why exactly are you not allowed to shrink the log? The typical reason for the recommendation to not shrink log files is because it will naturally grow to its normal size anyway, so there's no point. But if you're only stepping into the recommended practice of backing up the log anyway, it only makes sense to start by shrinking the oversized log first so that in the future your maintenance backups will keep it in its natural, comparatively smaller size.
Another EXTREMELY IMPORTANT point about shrinking, is that shrinking data files is another matter entirely. If you shrink a data file, you will be severely fragmenting all indexes and statistics on the database, making it mandatory to rebuild practically all the indexes on the entire database to avoid catastrophic degradation in performance. So do NOT shrink data files, ever, without consulting someone who knows what they're doing and is prepared to deal with the consequences. Log files are a lot safer in this regard since the fragmentation doesn't apply there.