February 19, 2010 at 1:04 pm
Hi,
Supose many users update the database "A"
the FULL backup for database "A" begin at 01:00 PM
the trx-log baclup for database "A" begin at 02:00 PM
the trx-log baclup for database "A" finish at 02:15 PM
the FULL backup for database "A" finish at 02:30 PM
Does some updated data can be ignored/missed in the .bak because trx-log backup run in the middle of the FULL backup ?
calico
February 19, 2010 at 1:25 pm
There is not point in running both backups same time, why don't you schedule t log after full backup? Yes, i think you will miss the updates, it will also slow down the full backup.
EnjoY!
February 19, 2010 at 2:12 pm
GT-897544 (2/19/2010)
There is not point in running both backups same time, why don't you schedule t log after full backup? Yes, i think you will miss the updates, it will also slow down the full backup.EnjoY!
While I agree that doing both backups at the same time seems somewhat counter-intuitive, I don't believe it will cause you to lose any data your full backup will contain everything you need in case of a failure at the moment of the end of the backup.
According to BOL a full backup is...
A full backup of the whole database. Database backups represent the whole database at the time the backup finished.
emphasis mine.
Also according to BOL you can do both at the same time, although log truncation will not occur...
Data Backup Operations and Restore Operations
Log truncation cannot happen during any backup or restore operation. In SQL Server 2005 and later versions, log backups can occur during a data backup. However, log truncation cannot occur during such log backups, because all of the transaction log must remain available to the data backup operation. If a data backup is preventing log truncation, canceling the backup might help the immediate problem.
The transaction log backup may/or may not slow down the full backup depending on how many transactions have changed, how you disk I/O is configured etc, in other words, It Depends!
Depending on your backup lengths and how busy your server is, you may need to do a transaction backup during your full window if you are concerned about a failure occurring during the full backup. This all depends on your SLA, your database, or backup devices. You can stripe your backups across numerous devices (files) to increase the speed of your full backup if this is needed as well.
-Luke.
February 19, 2010 at 2:14 pm
the full backup will be consistent at the point it finishes.
The t-logs will give you more granular recovery points during the time it takes the full backup to run. What would you do if you had a crash at 2:01?
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February 19, 2010 at 2:54 pm
Thank you LUKE !
calico
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