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Full Name: Marianne Laws

Exchange - truncation of logs

Post by mazl7 » Apr 23, 2019 7:08 am

Hi the Veeam backup of our exchange server is currently set to VSS Disabled and transaction logs - copy only. Following the backup each day, the datastore is replicated to an external server.

We currently have around 170 Gigabytes of exchange transaction logs on the exchange server which date back to December 2018, there is currently 40GBs space remaining on the drive of the transaction logs.

I would like to change the settings so that the logs are truncated, but I am not sure why the contractor that setup our system did not do this originally. Are there any repercussions for the backup and replication if I change the settings in order for the backup to process the logs? I would like to know if there are any issues I should consider, before I go ahead and make the changes. I would appreciate your advise. Thank you.

Andreas Neufert
Veeam Software
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Full Name: Andreas Neufert
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Re: Exchange - truncation of logs

Post by Andreas Neufert » Apr 23, 2019 9:18 am

Hi Marianne,

thanks for the request.
Transaction logs - copy only: This setting is needed if you backup Exchange with another application. Only one backup software should handle transaction logs and then delete it.
VSS disabled: If it is really disabled we would backup the server just crash consistent which I would not recommend. You need some space for the temporary VSS Snapshot on all disks. So if a disk is near full this could be the reason why someone disabled this to avoid backup failures. But Exchange is not in consistency state which is pretty bad for restore.

When you enable both, you need some space for the VSS disk software snapshots and as well the truncation of the logs will take it´s time. So I suggest you plan a maintenance window where the Exchange Server is reduced in performance because of the extra IO of the log truncation process.

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Re: Exchange - truncation of logs

Post by ejenner » Apr 23, 2019 9:21 am

I think the only potential sticking point is that big changes to the data are reflected in the time it takes for the job to complete and the amount of storage used in the repository. i.e. if you cause the job to truncate the logs they'll be rolled into the exchange database and may end up appearing to be different data, thereby increasing the amount of data held in the repository. For a while, depending on your backup retention settings, you will require more space on your repository to save the changes you're making. So have you got enough room to store the extra Exchange data just in case that problem appears?

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