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baber
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Truncate transaction logs

Post by baber » Jan 10, 2018 7:57 pm

Dear all

Hi
can you say me in simple with an example what is your means about truncate transaction logs ?
for example is this sentences " If you truncate transaction logs with Veeam Backup & Replication, the chain of transaction logs will be broken, and the Microsoft SQL Server log backup job will not be able to produce a consistent log backup "

BR
Babak

rhys.hammond
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Re: Truncate transaction logs

Post by rhys.hammond » Jan 11, 2018 4:49 am

Truncate meaning to delete. If logs records were never deleted from the transaction log, it would eventually fill all the disk space that is available to the physical log files.
Log truncation automatically frees space in the logical log for reuse by the transaction log.

Regarding the warning, It's not recommended to truncate logs with Veeam Backup & Replication if you use another backup tool which also truncates the logs.

For example, you can use Veeam Backup & Replication to create a VM image backup and instruct the native Microsoft SQL Server log backup job to back up transaction logs. If you truncate transaction logs with Veeam Backup & Replication, the chain of transaction logs will be broken, and the Microsoft SQL Server log backup job will not be able to produce a consistent log backup.
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baber
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Re: Truncate transaction logs

Post by baber » Jan 11, 2018 7:24 am

now in sql tab when enable application aware processing we have 3 choise:
1- truncate transaction logs
2-don't truncate logs
3-backup logs periodically

now i understand difference between case1 and case3 is:

in case1
it will truncate transaction logs on main vm after backup from vm has been finished and will be saved transaction logs in vm baclup file

in case3: after get backup from vm it will get a seprate backup from transaction logs and will be save them on repository seprately

are that correct?

rhys.hammond
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Re: Truncate transaction logs

Post by rhys.hammond » Jan 11, 2018 7:31 am

Yep pretty much.

Source: https://helpcenter.veeam.com/docs/backu ... 5#truncate

1 - If the job completes successfully, Veeam Backup & Replication produces a backup file or VM replica and truncates transaction logs on the original VM. As a result, you have the backup file or replica that contains a VM image at a specific point in time.
In this scenario, you can recover a database to the point in time when the backup file or replica was created. As transaction logs on the VM are truncated, you cannot use them to get the restored database to some point in time between job sessions.

2 - You can choose not to truncate transaction logs on the VM. This option is recommended if together with Veeam Backup & Replication you use another backup too

3 - To protect Microsoft SQL Server VMs, you can instruct the backup job to create image-level VM backups and periodically back up database transaction logs. If Microsoft SQL Server fails, you can restore the Microsoft SQL Server VM from the necessary restore point of the image-level backup. After that, you can use Veeam Explorer for Microsoft SQL Server to apply transaction logs and get databases on the Microsoft SQL Server to the necessary state between backups.
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baber
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Re: Truncate transaction logs

Post by baber » Jan 11, 2018 8:53 am

Can we say this mode is such as full or incremental backup forever forward inc backup just in this mode after get backup , truncate transaction logs from source vm but full or incremental backup is contain all transaction logs and for restore there is no difference between them if get backup in mode1 while we restored it will be restore with all transaction logs and when we get normal backup from sql machine without select this mode while restore that also will be restore with all of transaction logs

is that correct?
BR

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Re: Truncate transaction logs

Post by foggy » Feb 16, 2018 2:33 pm

Backing up transaction logs allows for using the granular point-in-time restore functionality available in Veeam Explorer for Microsoft SQL Server (restore up to a specific transaction).

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