What would happen if I delete the .ldf file that is in the same folder that my .mdf file?
The LDF file is the transaction log and is required for all SQL server configurations. Depending on the recovery mode, will determine how it is used. However all queries basically get stored here until successfully committed to the database (MDF).
You will not be able to delete it while SQL server service is running. You can detach the database, delete the log file (LDF) and reattach the data file (MDF). However it will just create a new log file. You really should not need to delete it. If it is getting too large you will need to manage it, typically through the backup process.
The database will be marked as suspect on SQL Server restart and inaccessible without some in depth fiddling to recover it.
The LDF is an essential part of the database: you need this file.
You can of course ignore us, and delete it and see for yourself...
As already pointed out, the .LDF file is crucial for the DB and the DB will not be available without one. The .LDF can be deleted only if the DB is offline, or detached or SQL Service is stopped.
Assuming that one of the above 3 scenario was true and you did delete the .LDF file, then the DB would be suspect when SQL server is restarted. If the DB was offline and you try to bring it back online, it will give you an error:
File activation failure. The physical file name "<<filename.ldf>>" may be incorrect.
Msg 945, Level 14, State 2, Line 1
Database '<<DB Name>>' cannot be opened due to inaccessible files or insufficient
memory or disk space. See the SQL Server errorlog for details.
Msg 5069, Level 16, State 1, Line 1
ALTER DATABASE statement failed.
It is quite simple to fix this error, but you will need to delete all the Metadata pertaining to the DB from system files. The easiest way to do that would be to drop the DB. Here is what you will need to do.
Take the DB offline or detach the DB
Make a copy of the .MDF file to your backup directory
Now Drop the DB (You will have to reattach the DB, if you detached, of course)
Copy the .MDF back to the original location
After these steps, run the following:
SP_ATTACH_SINGLE_FILE_DB #dbname='<<DBName>>'
,#physname=N'<<filepath\filename.MDF>>'
This should return you the following:
File activation failure. The physical file name "<<Filepath\filename.ldf>>"
may be incorrect.
New log file '<<Filepath\filename.ldf>>' was created.
That would bring your DB back to an usable state.
The million $$$$ question still remains - why would anyone want to delete the .LDF file???
Raj
The best way to keep the size of .LDF file in check is:
to regularly take transaction log backups at least once a day or
change your recovery model from full to simple ( by default, its full)
Related
I had stuck with one of our team issue where database drive size was overfilled due to log file which was around 150 GB and there was no hope of making any space on server. So, they had detached the database and then deleted to log file. But, then they were then not able to attach the mdf file. I then tried to rebuild log file but it was too not successful as there was no clean shutdown in database. Has anyone gone through this problem and successfully recovered the database?
sp_attach_single_file_db followed by a DBCC CHECKDB should do the trick. Any uncommitted transactions that might still be in that log file will be lost.
If you have an offline database in your metadata, delete that one first with DROP DATABASE but make sure you have a backup of your MDF file.
Suddenly I saw my SQL Server is in suspect/OFF Line mode. That's why I am not able to do any any operation in my db. For this reason I restarted my server (Windows Server 2003) .
But when I get ready I found that some of my data has been lost. I have no any back up of my db.
Is there any way to get back the data that I have lost.
the error log:
Could not redo log record (5108:10151:5), for transaction ID
(0:1552370), on page (1:3679), database '??'
The database may go in suspected/offline mode if the location of datafile and the log file have been misplaced accidentally or intentionally, and so after restart the database is unable to find its datafiles and goes in suspect or offline mode. This can be resolved by bringing the datafile and the log file back to the original path that has been configured for the database. After that, the database can be restored with no loss using the command 'Restore with recovery'. The original path for the datafile and the log file can be found in the error log of the server that contains the database.
Try the solution, hope it will help as it did for me.
In another case, the database may go in suspected/offline mode due to off and restart of the server in middle of a transaction and after the restart the transactions may not be committed or rolled back to a consistent state thus leaving database in an inconsistent state turning it suspected or offline. The solution for this is:
alter database <database name> set emergency dbcc checkdb (repair_allow_data_loss)
As the commnand itself states allow data loss, this command may result in loss of some data from the transaction log and hence we may face a data loss, so it is not recommended for a frequent or unapproved use.
In this case, I suggest you check your log file (LDF). In SQL, this log file records all the INSERT, UPDATE, and DELETE query operations performed on a database.
Suppose you have an LDF file. You can work with Restore and recovery process. I used this process for one of my existing clients & It worked.
https://learn.microsoft.com/en-us/sql/relational-databases/backup-restore/restore-and-recovery-overview-sql-server?view=sql-server-ver16
If you do not have a log file, you can use stellar repair for SQL this process helps me to recover my data many times.
Thanks
I want a copy of SQL Server transaction log file for "raw" analysis. What is the safest way to get a copy of that file without shutting down the database and disturbing the existing log/backups/backup schedules and just about everything.
FYI, Its a SQL Server 2000 database server and I can see the log file (its about 4GB in size) and I cannot copy it as is; I get the "access denied" error when copying from explorer or command line.
Can you not analyse the log file backups instead of the log file itself? If you must have a copy of the log file itself, restoring a backup of the database and all transaction logs will give you a replica of the transaction log file in a different database.
You cannot create a copy of a transaction log file, Although, you can create the backup of your database and restore it in another location with another name and then you can detach it.
My sql server marked one database as suspected , on checking i found my mdf,ldf files are missing, but no errors on chkdsk, what it means some virus ?
Either the files were deleted, or they have been moved and a master database backup restored from before the change in location. In both cases the physical files can only be deleted or moved if the database is offline - either because sql server was shut down or the database was closed.
Either of these things is highly unlikely to have happened accidentally. It's unlikely to be a generic virus or trojan as such would either have to specifically delete the files on startup before SQL Server started (assuming your database starts automatically) or shut down the database then specifically delete the files. Given that chkdsk doesn't report errors either it's unlikely to be a disk issue, so it's a virtual certainty that the cause of the error is deliberate database (mis)management.
I think the most likely option is that a dba has decided that the files should be moved elsewhere - typically this is done for space or performance reasons - for instance if a new drive is added to a machine that is running out of space then the database could be moved to that. For some reason a backup of the master database has subsequently been restored from a point before the move.
My first action would be to do a full scan of the system for all mdf/ldf files and (hopefully) locate them. I'd also do a scan of backups and look for the latest master database backup. You could either then try restoring the last master backup and see if that fixed the issue (i'd back up the current master first of course), and failing that, or directly, reattach the missing files.
If you cannot find the mdf/ldf files then your only option is restore from backup. If you don't have a backup then your database is lost.
http://support.microsoft.com/kb/180500
At startup, SQL Server attempts to obtain an exclusive lock on the device file. If the device is being used by another process (for example, backup software) or if the file is missing, the scenario described above will be encountered. In these cases, there is usually nothing wrong with the devices and database. For the database to recover correctly, the device must be made available, and the database status must be reset.
It means someone deleted the files.
They can not be deleted when in use so it happened:
when SQL Server was shut down
the database was closed (Express version usually)
the database was taken offline
All user dbs will share the same folder (edit) by default (end edit) so this is deliberate
The more exotic options include restoring the master db where the databases/MDF files listed in the restored master db do not exist etc. But I doubt it.
In this situation, you can check the SQL Server logs. Go to Management, Click on SQL Server Logs and click on current and check the message.
In my case, I got this:
Error 17207, severity 16, state 1 (it is related to log file deletion or corruption)
Solution:
Set the database into single user mode:
Alter database dbname set single_user
Now set the database into emergency mode:
Alter database dbname set emergency
Repair missing log file or corrupted log file with data loss.
DBCC CHECKDB ('dbname', REAPIR_ALLOW_DATA_LOSS)
Note: You may loss the data by using this command. It also depends on client's approval.
Now set the db in multi user mode;
alter database dbname set multi_user
In SQL Server suspect database is a mode when user unable to connect with database.
At this time user unable to perform any action and can not do anything like no open no backup and no restore etc.
Possible cause for this problem can be one of the following:
1. Database is corrupted
2. Insufficient memory state.
3. unexpected shutdown etc.
4. OS is unable to find the database file
I have an MDF file and no LDF files for a database created in MS SQL Server 2005. When I try to attach the MDF file to a different SQL Server, I get the following error message.
The log cannot be rebuilt because there were open transactions/users when the database was shutdown, no checkpoint occurred to the database, or the database was read-only. This error could occur if the transaction log file was manually deleted or lost due to a hardware or environment failure.
I would like to accomplish any one of the following options:
Attach the database without data loss (unlikely but would save me some time).
Attach the database with data loss (whatever transactions were open are lost).
Recover the schema only (no data) from the MDF file.
What SQL commands can I try to get my database going again?
I found the following document on Experts Exchange.
patrikt:
You will have data loss but it can be done.
1. Detach database and move your mdf to save location.
2. Create new databse of same name, same files, same file location and same file size.
3. Stop SQL server.
4. Swap mdf file of just created DB to your save one.
5. Start SQL. DB will go suspect.
6. ALTER DATABASE yourdb SET EMERGENCY
7. ALTER DATABASE yourdb SET SINGLE_USER
8. DBCC CHECKDB (yourdb, REPAIR_ALLOW_DATA_LOSS)
9. ALTER DATABASE yourdb SET MULTI_USER
10. ALTER DATABASE yourdb SET ONLINE
Here are details that cover parts 2) and 3) in case re-creating log doesn’t work which can happen if MDF file is corrupted.
You can recover data and structure only by reading MDF file with some third party tool that can de-code what’s written as binary data but even with such tools you can’t always do the job completely.
In such cases you can try ApexSQL Recover. From what I know this is the only tool that can do this kind of job but it’s quite expensive.
Much better idea is to try to recover these from any old backups if you have any.
FROM a post at SQL Server Forums Attaching MDF without LDF:
If you want to attach a MDF without LDF you can follow the steps below
It is tested and working fine
Create a new database with the same name and same MDF and LDF files
Stop sql server and rename the existing MDF to a new one and copy the original MDF to this location and delete the LDF files.
Start SQL Server
Now your database will be marked suspect 5. Update the sysdatabases to update to Emergency mode. This will not use LOG files in start up
Sp_configure "allow updates", 1
go
Reconfigure with override
GO
Update sysdatabases set status = 32768 where name = "BadDbName"
go
Sp_configure "allow updates", 0
go
Reconfigure with override
GO
Restart sql server. now the database will be in emergency mode
Now execute the undocumented DBCC to create a log file
DBCC REBUILD_LOG(dbname,'c:\dbname.ldf') -- Undocumented step to
create a new log file.
(replace the dbname and log file name based on ur requirement)
Execute sp_resetstatus
Restart SQL server and see the database is online.
UPDATE: DBCC REBUILD_LOG does not existing SQL2005 and above. This should work:
USE [master]
GO
CREATE DATABASE [Test] ON
(FILENAME = N'C:\MSSQL\Data\Test.mdf')
FOR ATTACH_REBUILD_LOG
GO
have you tried to ignore the ldf and just attach the mdf:
sp_attach_single_file_db [ #dbname = ] 'dbname' , [ #physname = ] 'physical_name'
i don't know exactly what will happen to your open transactions (probably just lost), but it might get your data back online.
-don
See here : Rebuild master and restore system databases from complete disk failure which has a very nice explanation
Just had this problem myself, but none of the above answers worked for me.
But instead, I found this which worked a treat and so I thought I'd share this for everyone else:
http://www.kodyaz.com/articles/sql-server-attach-database-mdf-file.aspx
Found a another way that works completely:
Create new database with same name to default database location.
Stop SQL server.
Copy old mdf file to overwrite newly created mdf file and delete new ldf file
Start SQL Server, database will be in emergency mode
Detach the emergency mode database
Copy original ldf file to default database location (where new LDF file as created and deleted under step 3 above.
Attach the database MDF file.
I got a working database after trying all of the above that failed for me.
I hope it is easy to do so,
Open SQL Server
Click New Query
Execute the following query
sp_attach_single_file_db #dbname='dbname',#physname='C:\Database\dbname.MDF'
Where dbname is you want to show in Object Explorer, where #physname is the local filepath location of your mdf file.
Hope it will help someone, i done by above, got both structure and also data.
Tested in Sql Server 2000 and 2008. In Sql Server 2000 it is not working, but works perfectly in 2008.