SqlTempLogPath needed space

[arosas]

Here's is what I have gathered so far with the log backup process that happens in a SQL VM.

When the child log job first runs, the SqlTempLogPath registry is created and set to the disk with the most free space available and never changed again.
The BAK files are Veeam BAK files not SQL BAK files
The BAK files consists of logs and are only placed in that location for transport to the log shipping server
The file is automatically removed after it's shipped, if it hasn’t shipped for whatever reason it will send it on the next interval.
The registry entry can be deleted and on the next log backup it will check free space again and set the entry to the disk with the most free space at that time.
You can set this to any local drive on the system.

https://helpcenter.veeam.com/backup/how ... ackup.html
https://www.veeam.com/kb2642

My question is, how much space is needed for this location and how would we determine this from previous log backups?
Keep in mind we run a active full backup weekly, so if more space is needed for this operation, let me know.

[Gostev]

It depends on how often you run transaction log backups. The more often you have it scheduled, the less temp space you need. For example, every 5 minutes vs. every 1 hour means 12 times difference in the size of a transaction log generated between log backup cycles.

Size of VLB file = size all log backups taken between consequent image-level backups (which are typically done daily), compressed.

[arosas]

I am running my log backups for this VM every 20 minutes with a log retention of 30 days.
I looked through all 40 VLB files on the repository and the largest one we have is 20.6GB.

Is it safe to say that the most I will need would be roughly 20GB of free space for the temp directory?

[Gostev]

20GB is all log backups between consequent image-level backup runs, which you are probably doing daily. Basically, you only need enough disk space to store the native log backup containing 20 min worth of transaction logs. This native backup will then be picked up and shipped onto the backup repository. For safety reasons you may want a few times this amount perhaps, so that you don't run out of disk space if a few log backup cycles are skipped due to some backup infrastructure component being temporarily unavailable.

[arosas]

Thank you Gostev, this is perfect. Greatly appreciate your reply.

[MCH_helferlein]

Hi everyone.

Since the C got filled up by the SQL Transaction logs I have added a separate Disk named V:\ like Veeam
Added the SqlTempLogPath Regkey with V:\ on the SQL Server.
Now Veeam copied a lot of bak files and puts loads of XLM files into that separate Disk, so it seems like Veeam Agent did pick up the new path.

While doing transaction logs now there are warnings like:

Failed to save SQL Server transaction log backup file for database XXX to repository. Failed to open backuped log storage. Path 'V:\' doesn't exist.

But it says also that:
Saving 869.1 MB of transaction logs to backup repository

Somebody has a hint here why the Transaction logs now does not find that path?
Might it be a problem that there is no other path like V:\sqltemp or something?

Thanks

[MCH_helferlein]

So ok... one should sometimes read the manual... shame on me!

In the Veeam KB: https://www.veeam.com/kb2642 is clearly written:

Key: HKLM\SOFTWARE\Veeam\Veeam Endpoint Backup
Type: REG_SZ (String Value)
Name: SqlTempLogPath
Value: Path to desired location (without trailing backslash)

WITHOUT trailing backslash... so I changed V:\ to just V: and it works now