No free storage error

Hi, i found in bluecherry system log

Nov 7 16:54:56 elf-nvr bc-server[26943]: W(): Cannot remove file /mnt/sdb/2022/09/27/000008/09-15-02.mp4 for cleanup: Permission denied
Nov 7 16:54:56 elf-nvr bc-server[26943]: E(): Cleaned up 0 files with 100 errors, which may cause undeletable files
Nov 7 16:54:56 elf-nvr bc-server[26943]: E(1/cam1): No free storage locations for new recordings!
Nov 7 16:54:56 elf-nvr bc-server[26943]: E(1/cam1): Cannot start recording!

What i have to do to fix it? How to clean recordings database and start from scratch?
As far as i understand, if i have to unmount disk, format it and mount back, it will confuse BlueCherry, an seems like wrong way?
What are the right ways to maintenance for storage drive? I have dedicated HDD for BC
Screenshot_2022-11-07_17-04-05

I has stopped BC service, unmount drive, made check for errors, and it reports disk is ok, it does not helps.
Screenshot_2022-11-07_17-05-35

Solution i found:
created new root folder “/dvr”, assigned ownership and permissions,
set it as storage location in BC,
deleted old folders.
Hope it was right )
But I am still interested in the causes of this problem.

Sounds like the there is a permission problem where the files weren’t able to be deleted. If this continues I’ll need more information about the mount point and permissions.