We have two home security systems and both of them are from ALDI; the main house system and another one in the workshop.
The workshop DVR has HDD failures from time-to-time so it's become a familiar routine to pull out the unit, remove the HDD and connect to workshop PC to fix it - but not format. Do that when it's back in the DVR the connect a test camera to make sure it records OK before putting it back in the cupboard.