I have a problem using the AWS Database Migration Service for implementing a transactional replication from SQL Server as a source database engine, a help is highly appreciated.
The 'safeguardPolicy' connection attribute defaults to 'RELY_ON_SQL_SERVER_REPLICATION_AGENT'. The tools will start mimicking a transaction in the database for preventing the log to be reused and to be able to read as much changes from the active log.
But what is the intended behavior of these safeguard transaction? Will those sessions be stopped at some point? What is the mechanism to start / run for some time / stop such a transaction?
The production databases I manage are in Full recovery mode, with Log backups on each half an hour. The log grows to an enormous size due to the inability for a valid truncation procedure to succeed and because of those safeguard transactions initiated by the DMS tool.
The only solution to a full transaction log due to LOG_SCAN caused by such behavior of DMS for now is to stop the DMS tasks and run a manual truncation of the log, to release space not used. But it is not a solution at all if we need to stop the replication each time such a problem occurs, knowing that it will occur often.
Please share some internals about the tool if possible.
Thanks
I have a SQL Server database with one log file and it is growing very fast.
But it is happening after I shrink the file before that it was good.
My database recovery model is FULL recovery.
Please help with it.
Assuming you meant transaction log...
If you use FULL recovery model,
to reclaim a space in the transaction logs or shrink it, the log (or database) should be backed up first. If you use also CDC or Replication, even backup is not enough. The space can be reclaimed only after Log Reader Agent read the transaction logs.
The transaction log is growing fast if there are many DB changes.
It sounds like the log file was appropriately sized for your traffic before you shrank it. To paraphrase Elsa from the movie Frozen "Let it grow!". That is, unless you had an event that you can point to that made the it much larger than it typically is, the log file will likely be appropriately sized given your transactional volume.
I am not a DBA but a programmer. Recently we have been getting LOG SUSPEND issue daily on our production. I am unable to catch the scenario as it is not reproducible on my local system.
A file when uploaded on production fails with log suspend while same file uploaded on local seems to work fine. Also, when the same file is uploaded again after some time it seems to work fine in production too.
Really confused as why this is happening.
Log Suspend indicates that the transaction log is filling up, and may not be properly sized for the transaction rate you are supporting. Have the DBA/System Administrator add additional Log device space to the database that is having issues. If possible, you may also want to break up any large transactions as well to lower the possibility
As for a cause, it's very dependent on how the system is setup. First check the database settings.
sp_helpdb will print out the list of databases on the server, as well as any options that may be set for each database.
If you don't see trunc log on chkpt, then the database is setup for maximum recoverability, the log space will only free up after a backup is run, or after the transaction log is dumped. This allows for up to the second recovery in the event of a failure, at the expense of using more log space.
If you DO see trunc log on chkpt, then the database will automatically truncate the log after a checkpoint occurs in the database. Checkpoints are issued by the database itself as part of routine processing, but the command can also be issued manually. If this option is set, and the database still goes into log suspend, then you may have a transaction that did not properly close (whether by committing or rolling back). You can check the master..syslogshold table to find long running transactions.
A third possibility is that if the system is using SAP/Sybase Replication Server, there is actually a secondary truncation point used as part of the replication processes. The system will not truncate the transaction log until after a transaction has been read by the RepAgent process, so this too can cause a system to go into log suspend.
This question might be kind of elementary, but here goes:
I have a SQL Server database with a 4 GB log file. The DB is 16GB and is backed up nightly.
Can I truncate the log regularly because the entire DB+Log is backed up each night?
you can something like this to you maintenance schedule to run every night before the backup. This will try to shrink/truncate your log file to 1 meg
BACKUP LOG DBNAME
TO disk = 'D:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Backup\DBNAME.log'
DBCC SHRINKFILE('DBNAME_Log', 1)
Are you sure the log is backed up nightly and not just the database?
If so, then what does this database do? Are you deleting and refreshing whole tables? If so, your log might be the right size for the amount of transactions you have. You want the log to be large enough to handle your normal transaction load without having to grow. A small log can be a detriment to performance.
If this database is not transactional in nature (i.e., the tables are populated by full refreshes rather than one record ata time), the change the recovery mode to simple. Do not do that though if you have transactional tables that you will need to be able to recover from the log rahter than simply re-importing the data.
If you can run log backups during the day (depending on load, etc. this may or may not be possible for you) you can keep the log file under control by doing so. This will prevent the log file itself from growing quite so large, and also provide the side benefit of giving you the ability to restore closer to the point of failure in the event of a problem.
You'll still need to shrink the log file once using DBCC SHRINKFILE, but if it's backed up regularly after that point it shouldn't stabilize at a smaller size.
So our SQL Server 2000 is giving me the error, "The log file for database is full. Back up the transaction log for the database to free up some log space."
How do I go about fixing this without deleting the log like some other sites have mentioned?
Additional Info: Enable AutoGrowth is enabled growing by 10% and is restricted to 40MB.
To just empty it:
backup log <dbname> with truncate_only
To save it somewhere:
backup log <dbname> to disk='c:\somefile.bak'
If you dont really need transactional history, try setting the database recovery mode to simple.
Scott, as you guessed: truncating the log is a bad move if you care about your data.
The following, free, videos will help you see exactly what's going on and will show you how to fix the problem without truncating the logs. (These videos also explain why that's such a dangerous hack and why you are right to look for another solution.)
SQL Server Backups Demystified
SQL Server Logging Essentials
Understanding Backup Options
Together these videos will help you understand exactly what's going on and will show you whether you want to switch to SIMPLE recovery, or look into actually changing your backup routines. There are also some additional 'how-to' videos that will show you exactly how to set up your backups to ensure availability while managing log file sizing and growth.
ether backup your database logs regularly if you need to recover up to the minute or do other fun stuff like log shipping in the future, or set the database to simple mode and shrink the data file.
DO NOT copy, rename, or delete the .ldf file this will break your database and after you recover from this you may have data in an inconsistent state making it invalid.
I don't think renaming or moving the log file will work while the database is online.
Easiest thing to do, IMO, is to open the properties for the database and switch it to Simple Recovery Model. then shrink the database and then go back and set the DB to Full Recoery Model (or whatever model you need).
Changing the logging mode forces SQL Server to set a checkpoint in the database, after which shrinking the database will free up the excess space.
My friend who faced this error in the past recommends:
Try
Backing up the DB. The maintenance plan includes truncation of these files.
Also try changing the 'recovery mode' for the DB to Simple (instead of Full for instance)
Cause:
The transaction log swells up due to events being logged (Maybe you have a number of transactions failing and being rolled back.. or a sudden peaking in transactions on the server )
You may want to check related SO question:
How do you clear the transaction log in a SQL Server 2005 database?
Well you could take a copy of the transaction log, then truncate the log file, which is what the error message suggests.
If disk space is full and you can't copy the log to another machine over the network, then connect a drive via USB and copy it off that way.
You have the answer in your question: Backup the log, then it will be shrunk.
Make a maintenance plan to regularly backup the database and don't forget to select "Backup the transaction log". That way you'll keep it small.
If it's a non production environment use
dump tran <db_name> with no_log;
Once this has completed shrink the log file to free up disk space. Finally switch database recovery mode to simple.
As soon as you take a full backup of the database, and the database is not using the Simple recovery model, SQL Server keeps a complete record of all transactions ever performed on the database. It does this so that in the event of a catastrophic failure where you lose the data file, you can restore to the point of failure by backing up the log and, once you have restored an old data backup, restore the log to replay the lost transactions.
To prevent this building up, you must back up the transaction log. Or, you can break the chain at the current point using the TRUNCATE_ONLY or NO_LOG options of BACKUP LOG.
If you don't need this feature, set the recovery model to Simple.
My dear friend it is vey important for a DBA to check his log file quite frequently. Because if you don't give much attention towards it some day it is going to give this error.
For this purpose you have to periodically take back up so that the logs file would not faced such error.
Other then this the above given suggestion are quite right.
Rename it it. eg:
old-log-16-09-08.log
Then the SQL server can use a new empty one.