SAS Viya mirrormgr to download only deltas when downloading an update

[EyalGonen]

Hi experts,

I have downloaded a mirror from LTS 2025.09 with release X 

Now I want to download same LTS 2025.09 version but with a newer release for example release Y (Y > X)

Can I point mirrormgr to the same path I used when I downloaded release X and hopefully it will download just the files that have changed between release X and release Y? Also should I expect only a small files to be changed or is it that with each release all files are changed?

[gwootton · Accepted solution]

Yes, mirrormgr will only pull/push blobs not already present in the supplied local and remote repository, so if the command is stopped during mirroring you don't need to start over. Typically for releases within a cadence version only a subset of the images are changed, so mirroring a new release of the same version should be much faster if you supply the same local path.

[EyalGonen]

One more question...

For dark-sites I need to virus-scan the mirror before I can use it in the on-prem deployment.

If mirrormgr downloads only the "deltas" when I point it to an already downloaded mirror (as in the case of a new release within a cadence version) the question is how to can I detect which files it downloaded and virus-scan only those instead of having to virus-scan the entire mirror which can be dozens of GB in size?

[gwootton]

You could use the creation timestamps of the files in the local repository to determine when the individual blobs were downloaded (sas_repos/docker/v2/blobs)

[EyalGonen]

Hi @gwootton 

Are you sure new files are downloaded only in this folder sas_repos/docker/v2/blobs and no other folders?

I wonder if there is an option in mirror manager to print out which files it has download (maybe in its log?) and hopefully then to automatically ZIP or TAR them for sending to virus-scanning. This would have been very useful.

[gwootton]

No, new files are not only downloaded to the blobs path, but the blobs are the files that make up the images. There are also manifest files that indicate which blobs apply to which images, as multiple images use the same base. I'm not aware of any option to capture the downloaded files within mirrormgr into an archive, but again you could identify files based on their modification datetime to build such an archive.