As I suspected, it’s based in the VSS subsystem (source) which also explains it’s async nature. The de-dupe chunks are stored in \System Volume Information\Dedup\ChunkStore\*, with settings in \System Volume Information\Dedup\Settings\*. This has significant impacts to how your backup software interacts with such volumes, which is explained in the linked article (in brief: w/o dedupe … Read more
Deduplication does work. With deduplication, Size on disk field becomes meaningless. The files are no longer usual “files” but reparse points and don’t contain actual data but metadata for dedup engine to reconstruct file. It is my understanding that you cannot get per-file savings as dedup chunk store is per volume so you only get … Read more
The System Volume Information directory should be excluded using the /XD switch. Probably a good idea to exclude other hidden/system directories such as $RECYCLE.BIN.
You can use the zpool status -D poolname command. The output would look similar to: root@san1:/volumes# zpool status -D vol1 pool: vol1 state: ONLINE scan: scrub repaired 0 in 4h38m with 0 errors on Sun Mar 24 13:16:12 2013 DDT entries 2459286, size 481 on disk, 392 in core bucket allocated referenced ______ ______________________________ ______________________________ … Read more