I have a backup which in file explorer is roughly 160GB.
If I run
select sum((size*8)/1024) From sys.database_files where type=0
I get a result of 169493, fine.
When I try to restore this database to another server (the old DBA set up a job which restores the database automatically each morning from the latest backup, then runs
DBCC CHECKDB on it) it fails. If i try
RESTORE VERIFYONLY it turns out I need 288GB in order for this to work. Why? The backup is not compressed.