Failed Backup Transaction Log

alecl

I got this backup error e-mail for my log shipping transaction log backup:

SQL Backup log file
9/2/2007 1:45:00 PM: Backing up mydb (transaction log) to:
9/2/2007 1:45:00 PM: X:\dbbackup\Logs-Shipping\LOG_mydb_20070902134500.sqb

9/2/2007 1:45:00 PM: BACKUP LOG [mydb] TO DISK = 'X:\dbbackup\Logs-Shipping\<TYPE>_<DATABASE>_<DATETIME YYYYmmddhhnnss>.sqb' WITH NAME = '<AUTO>', DESCRIPTION = '<AUTO>', ERASEFILES = 3, MAILTO_ONERROR = 'admin@mycompany.com', COPYTO = '\\reportdb\logship-incoming', COMPRESSION = 1

9/2/2007 1:45:03 PM: Thread 0 error:
Error 620: Error writing to backup file(s).
9/2/2007 1:45:03 PM: Warning 210: Thread 0 warning:
Warning 210: Error writing to backup file: X:\dbbackup\Logs-Shipping\LOG_mydb_20070902134500.sqb
Warning: System error (The parameter is incorrect) Processed 12886 pages for database 'mydb', file 'mathxl_log' on file 1.
BACKUP LOG successfully processed 12886 pages in 1.854 seconds (56.936 MB/sec).

The Event Log had this:

Event Type: Error
Event Source: SQLVDI
Event Category: None
Event ID: 1
Date: 9/2/2007
Time: 1:45:03 PM
User: N/A
Computer: DBCLUSTER2
Description:
SQLVDI: Loc=SignalAbort. Desc=Client initiates abort. ErrorCode=(0). Process=2560. Thread=1072. Client. Instance=. VD=Global\SQLBACKUP_97F79214-C65B-4F9B-9E1F-6DBA7CF4FB8C_SQLVDIMemoryName_0.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

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I'm running Sql Backup 5.1.

This was a problem because it broke my log chain for log shipping purposes because the backup file was corrupt yet the LSN was incremented and I had to do a resync to get log shipping going again.

Why does it successfully process the backup if an error occured? If it just retried in case of an error it would have been less trouble. I have no idea why the error occured in the first place. I ran a DBCC checkdb to confirm my DB is ok and I've experienced no other issues.

petey

What was the size of the corrupted backup file? Can you send it to me for analysis?

It appears that SQL Backup failed to write to the destination drive, the very last block of compressed data. SQL Server has passed all the backup data to SQL Backup, which is why it reported a successful backup.

SQL Backup doesn't write each compressed block of data to disk immediately. It only writes to disk when its buffer (4 MB) is full, or when the backup has completed and there is still data in the buffer. In your case, the backup has completed, and SQL Backup attempted to write the remaining compressed data to disk but failed. It may have been due to a disk or network issue (if x:\ is a network share).