On Tue, 2026-09-15 at 07:08 +0530, Brajendra Pratap Singh wrote: > I have performed the production database upgrade from postgresql 13 to 17 > version > using pg_upgrade --link method on ubuntu 22.04 successfully. > > Now after few days of upgrade, while dropped one database of size 900+ GB > successfully, the space not get reclaimed physically from mount point > /usr/pgdata. > > Old PG13 data directory: /usr/pgdata/data1 --> size 4.5TB > > New PG17 data directory: > /usr/pgdata/data17 --> 5.6GB > > I didn't perform the delete_old_cluster.sh yet. > > I can see that the oid of this dropped database is present in PG13 data > directory > base location and occupying 972GB size, while it's not present in PG17 data > directory base location. > > Now my doubt is if I removed Old data directory, will it cause any impact on > running PG17 cluster. > > Please suggest the best and safe approach to reclaim the space.
Just go ahead and remove the old cluster. With pg_upgrade --link, the data files exist only once, but are linked in the data directory on both the old and the new server. Try du -sm /path/to/old/cluster /path/to/new/cluster and the old cluster will appear large, while the new cluster will seem small But if you run du -sm /path/to/new/cluster /path/to/old/cluster the new cluster will look big, and the new one will look small. That is because the same files are referenced in both directories. Yours, Laurenz Albe
