April 27, 2012 at 12:50 am
...there's always a catch....
i just tried the 'MIRROR TO DISK' on a small database, I get an error message about mirror not being supported on this version of sql server....
Ho hum, back to doing 2 backup tasks in the maintenance plan I think....
April 27, 2012 at 9:05 pm
anthony.green (4/24/2012)
two waysyour right, it wont speed anything up but if you backup twice the first backup is worthless as you cant apply any tx logs to it after you have taken the second backup so your first backup is only valid for restoring in the period it takes to backup the database a second time.
Please note that this information is incorrect. One of the reasons for keeping older Full Backups and Transaction Log Backups is to give multiple recovery paths and to also cope with corruption in a full backup.
In the situation described:
(a) Full Backup at T1.
(b) Full Backup at T2
(c) Log Backup at T3
Then recovery to time T3 can be done by either
Restore Fullbackup from T2 + Transaction Log backup at T3 or
Restore Fullbackup from T1 + Transaction Log backup at T3
In order to use a full backup as the base of a Recovery the only requirement is to have an unbroken Transaction Log Backup Chain from the time of the backup until the desired recovery time.
The confusion may have risen from including Differential Backups. If a diiferential backup is being used then this can only be applied after the most recent Full Backup.
For example, if a Differential Backup was taken between T2 and T3 then the only valid restore sequence (that uses the differential backup) would be:
Restore Fullbackup from T2 + Dfferential Backup + Transaction Log backup at T3.
You can look at http://msdn.microsoft.com/en-us/library/ms179436(v=sql.105).aspx for more information
Viewing 2 posts - 16 through 17 (of 17 total)
You must be logged in to reply to this topic. Login to reply