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Home > Archive > SQL server exams > May 2002 > Backup the active transation log?
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Backup the active transation log?
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| coronelbrown 2002-03-07, 1:24 pm |
| In the answer of a cuestion on a Transcender exam (SQL 7 Design) it says that to make a backup of the active part of the transaction log is necesary to have access to the transaction log itself and to the primary file. I thought that having access to the log was the only need! Can anyone explain me why I need access to the primary file? Thanks | |
| mrutgers 2002-03-09, 11:30 am |
| Don't forget that 'the transaction log' can mean more than one file, that you can choose to give your log file any (reasonable) name you like, and and that the entire set is treated as one logical unit. SQL needs to store all that information somewhere!
According to BOL topic 'Microsoft SQL Server 7.0 Storage Engine Capacity Planning Tips': A primary file is the starting point of the database and contains the pointers to the rest of the files in the database. | |
| BOLAJIKAMORU 2002-05-04, 12:45 pm |
| I want to believe the reason is because you are trying to backup an active log. You therefore need to have access to the primary file which contains the startup information for the database. Otherwise, access to the Transaction Log would have been the only requirement for the task. | |
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Originally posted by coronelbrown
In the answer of a cuestion on a Transcender exam (SQL 7 Design) it says that to make a backup of the active part of the transaction log is necesary to have access to the transaction log itself and to the primary file. I thought that having access to the log was the only need! Can anyone explain me why I need access to the primary file? Thanks
I don't know the question, but here's what I think anyway.
If you have several files spread out on different disks, and you have backed up individual files or filegroups, and one of the disks fail, you only want to restore the files that were affected by the failed disk, right?
Now, the first thing you do is - restore those files that were on the failed disk. Then, to make sure that the data in those files are consistent with the data on the other files, you need to reapply any transactions that took place since the file was backed up. Otherwise the file won't be as current as those files that were not affected by the disk failuer.
Just my €0,02. | |
| hard_coder 2002-05-08, 1:22 pm |
| in sql 7 you do need the primary file group to backup the trans log. It does have to do with references to where things are held. This no longer is true in SQL 2K, for the references are no longer in the primary file. They are kept in the master database. The was a good move because if your primary file got corrupted and your backup is botched you're screwed. Of course, if the master gets botched you have to rebuild it but highly unlikely to happen. |
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