Many reasons, like hardware failure, software issues, or power outage, can cause MS SQL to crash. When this happens, your database may enter suspect mode or recovery pending mode. And your database becomes unavailable. Sometimes, you may face random inconsistency errors when trying to open tables in the database. In this article, we will discuss tested and tried methods to recover SQL Server databases after an unexpected crash.
Causes of Unexpected SQL Server Crash
Your MSSQL can fail to open or crash due to several reasons. Some of them include
- Bugs in the SQL server software or conflicts with other software on the system.
- Bad sectors on the hard drive hosting your server
- Malware or virus infection on the system where the server is saved.
- Sudden power failure
What happens when the SQL Server suddenly crashes?
Corruption in the database is one of the notable results of a SQL Server crash. This usually occurs when:
- Transactions that were in progress remain incomplete.
- Database pages fail to be written to disk.
Some SQL users have confirmed that the state of the SQL database may suddenly changes to Recovery Pending or Suspect .
How to Restore MS SQL Database after a Sudden Server Crash?
Some methods are listed below to restore or repair the corrupt database files after a crash:
1-Restore the Database from Backup
The most preferred method to restore the damaged database is to use the last known backup. But this is only helpful when the backup file is readable. Here's how to restore your database from a backup file in MS SQL:
RESTORE DATABASE EmployeesComp34
FROM DISK = 'D:\BackupSQL\ EmployeesComp34.bak'
WITH FILE = 1,
MOVE ' EmployeesComp34' TO 'D:\BackupSQL\ EmployeesComp34.mdf',
MOVE ' EmployeesComp34_log' TO 'D:\BackupSQL\ EmployeesComp34.ldf',
REPLACE,
STATS = 10;
If you want to restore .bak file by step-wise, with fewer errors, then you can use SQL Server management
Restrictions and limitations of this method
- You cannot restore a database backup from a newer SQL Server version to an older version.
- No active connections are allowed.
- Must use WITH MOVE if paths differ
- Disk space must be sufficient
- Corrupted backup cannot be restored
- Collation differences may cause issues
- Backups require a large amount of disk space to restore backups
- Cannot restore log/diff without a full backup
2-Use DBCC CHECKDB Command to Repair SQL Database
If your backup is not available, then you can use the DBCC CHECKDB command in SQL Server to repair a corrupt database after a sudden crash. It can help you recover a database when it enters suspect or recovery pending mode . To use the DBCC CHECKDB repair command, your database should be accessible. If it is not, then you can first set the database to EMERGENCY mode. After this repair, run the following command:
- Change the database state to SINGLE-USER mode
ALTER DATABASE EmployeesComp34 SET SINGLE_USER
- Next, use the repair option, like REPAIR_ALLOW_DATA_LOSS, with the DBCC CHECKDB command as given below:
DBCC CHECKDB (N ’ EmployeesComp34’, REPAIR_ALLOW_DATA_LOSS) WITH ALL_ERRORMSGS, NO_INFOMSGS;
GO
Restrictions and limitations of this method
- Repairing using DBCC CHECKDB with REPAIR_ALLOW_DATA_LOSS may cause data loss
- Must run in single-user mode for repair
- Cannot recover specific objects
- It reallocates the pages; thus, it does not guarantee complete recovery.
- Needs a large tempdb space
3-Use a Professional SQL Recovery Tool
If the backup file is not available and the pages in the database file are severely corrupted then you can use a professional MS SQL recovery tool like Stellar Repair for MSSQL. It quickly repairs MDF/LDF files of any size and of any MS SQL version, without the need for resizing or reconfiguration of tempdb. Also, it guarantees the complete data recovery including pages and stored procedures. Also, it allows you to recover a specific object from the corrupt database with complete precision.
How to restore a corrupt SQL database using Stellar Repair for MSSQL?
To restore a corrupt SQL database, download, install, and launch Stellar Repair for MS SQL, select the corrupt MDF/NDF file, run the repair, preview recovered objects, and save them back to SQL Server.
Why should you use a SQL recovery tool to recover SQL databases after a crash?
You should use Stellar Repair for MSSQL because it.
- Quickly recovers databases even from severe corruption that native tools cannot fix.
- Works independently of tempdb space, avoiding large resource requirements.
- Ensures complete recovery of SQL database tables, indexes, triggers, stored procedures, and more.
- Allows you to recover specific objects instead of the entire database.
- Supports all advanced MS SQL versions.
Conclusion
SQL Server may crash due to disk failures caused by logical or physical issues. Often, crashes occurs due to logical errors such as file system errors, virus or malware infection, abrupt shutdown, device driver issues, etc.
A sudden server crash often results in corruption in the SQL database. You can use a powerful SQL database recovery software such as Stellar Repair for MS SQL. It is a DIY tool to help you easily recover data that gets corrupted after a failed, crashed system or server. It does not rely on large tempdb space to perform repairs.
