REFS & Synthetic Full Backups - File Cycling Question

[colsztyn]

So, I have upgrade our B&R 9.0 to 9.5 and upgraded to Windows 2016, redid the repository to REFS with 64K blocks and all is running well. I have decided to run a Synthetic Full on each Saturday, which is utilizing the Fast Clone without issue. It did, however, get me to wondering about how B&R 9.5 is handling file retirement in the case of the original Active Full VBK that is being leveraged by the Synthetic Fulls for Fast Clones once the original Active Full hits its backup retention window and is slated for deletion.

This question would also apply, I assume, for anyone who manually deletes (on the fly) an older VBK that may be the original Active Full to free up drive space on an emergency basis but doesn't do it within the B&R client, so the Veeam software has no way to know that the Active Full is going to be deleted and thus do whatever technical process it would undergo to assure those blocks are still available to the remaining Synthetic Full backups.

Any light you can shed on this question will be appreciated.

[Gostev]

Glad to hear ReFS is working well for you!

I *think* I understand your question, sorry if not.

The process is actually not in Veeam, but in ReFS itself. For Veeam, it is totally transparent.

While that active full will indeed be deleted from the file system by Veeam, ReFS will preserve those of its blocks which are a part of other existing files (synthetic fulls) because they will still have a reference count above 0. Only those blocks not belonging to any other files (as of after active full deletion) will be deleted.

[colsztyn]

Thanks, Gostev. I was wondering if that might be the case, but thought I would ask for some confirmation. It is an important question, I think, as we live into the new ReFS paradigm because who is managing the data blocks that the synthetics are relying on to actually function is important (to state the obvious).

Anyway, let me just say that the only piece of vendor technical news I read religiously is your Sunday evening newsletter. Always informative and sometimes saves a significant issue before it becomes one! Kudos on the nice work and don't ever stop writing it!

[Gostev]

No problem. Thanks for your kind words, music to my ears!