LiteSpeed does not properly handle COPY_ONLY backups.
Currently SmartCleanup never deletes copyonly backups (by design)- but also does use them when creating backup chains and determining dependencies...
There are two ways that this manifests a problem:
1) copyonly transaction log.
(a) Full backup
(b) tlog backup
(c) tlog copyonly backup
Under this scenario- backup (b) can not be removed while (c) is a dependent- but (c) will never be removed since it is copyonly
2) copyonly full with diff
(a) full backup
(b) full copyonly backup
(c) diff backup
Under this scenario- if backup expiration time is set between backups (a) & (b), then full backup (a) can be removed since backup (c) is errantly marked as depending on (b)- It really depends on (a) since (b) is copyonly
Fixed in a future version of LiteSpeed