B&R 9.5 ReFS / Fast Clone and Storage Use

[bernd.dausch]

Hello,

I have created a new Repository on a NAS System with Windows Storage Server 2016 and ReFS.

We moved existing Backup Jobs to the new Repository and Create a new Backup Chain.
The First Backup was a Full. Some of the Backup Job have an syntetic Full on the next day.

The two VMs in the Job have a Size off 170 GB, the Full Backup Job has a file size of 50 GB.
the fast clone by the syntetic full job on the next day work like a charm in 42 Seconds and has a size of 50 GB too.
The Properties of the two files says 100 GB on disc.

As i unterstand the fast cloning process merged the identical Blocks, so the used space on the disc
must be significant smaller. The Transferred Space by the inkremental Backup Job is 6 GB (24,5 GB read).

Have i missed a setting / step or is this normal?

Regards,

Bernd

[tdewin]

If you look at the files themselves, they will not be smaller. However if you take the size of all the files (e.g properties of the repository directory) and then compare it with the disk space usage (this pc overview), the repository size should be bigger then the disk space usage

In the end we just tell refs to clone blocks. ReFS doesn't really clone them but puts pointers. Other then that, the files looks just like regular files. So if you copy them to NTFS, they are still usable, just in this case, you will be using the complete size again on disk

Finally, increments are inherently different then previous points so most savings will be done on the Full backups

[bernd.dausch]

thank you for the info, I wait for more Full backups in the Repository and watch again.