I’ve been also thinking a lot the compaction. I made suggestion for the same goal, but from different point of view: Compact - Limited / Partial
Yet for your situation, my best suggestion is to keep small volumes. Because you don’t need to download for compacting, if you’re just deleting obsolete volumes. If volume and deduplication block size are the same, then there’s no need to download any blocks to release blocks. - I’m not saying it would be practical solution for all cases, but in some cases it could be. Like with my backup sets, where I backup disk images and other large archives. Which aren’t basically ever modified, nor there’s anything to deduplicate. So using huge “dedupe block” solves this issue.
- compression probably allows still multiple deduplication blocks in a volume, if blocks are very highly compressible. - Yet in my case, the data is already precompressed and encrypted, so this isn’t the case and I’ve disabled compression.