Build the Right NAS for Surveillance
This preset uses the camera-retention estimator and gives surveillance workloads a larger reserve.
What do you mainly want your NAS to do?
Choose one primary workload. You can add secondary workloads below.
What this builder sizes for surveillance
A CCTV NAS is sized by a different equation from a file server: camera count × bitrate × retention days. The builder uses a camera-retention estimator and gives surveillance a larger capacity reserve, because footage is written continuously, 24/7, and you rarely delete it before the retention window closes. More cameras or a longer retention window both push capacity up quickly, so this is one build where you plan generously.
Why surveillance drives, not ordinary NAS drives
This is the one use case where the standard "buy an IronWolf" advice changes. Surveillance drives — WD Purple and Seagate SkyHawk — are tuned for a very different workload: many simultaneous sequential write streams, all day, every day, with firmware (ATA streaming) that prioritises smooth recording over the random-access speed a general NAS wants. A regular NAS drive works, but a surveillance drive handles the sustained multi-camera write load with less risk of dropped frames, which is why NVR vendors specify them. We keep surveillance drives out of the general NAS tables on purpose, because they are the wrong choice for everything except this.
Bays, RAID and the 24/7 write load
Because a surveillance array writes constantly, fault tolerance matters and rebuild risk is real: use RAID 5/SHR for four drives, and step to RAID 6/SHR-2 once you have five or more, so a second drive failing during a rebuild does not lose weeks of footage. Size the usable capacity in the RAID calculator, then add cameras and retention on top. A UPS is worth it here too — an unclean shutdown mid-write is exactly what a recorder should avoid.
Frequently asked questions
How much storage does a surveillance NAS need?
It is driven by camera count × bitrate × retention days, and footage is written continuously, so capacity adds up fast. Plan generously and size the usable space in the RAID calculator; more cameras or a longer retention window both push the requirement up quickly.
Should I use special drives for a surveillance NAS?
Yes — WD Purple or Seagate SkyHawk surveillance drives. They are tuned for many simultaneous sequential write streams 24/7, with firmware that prioritises smooth recording. Ordinary NAS drives work but handle the sustained multi-camera write load less gracefully, which is why NVR vendors specify surveillance drives.
What RAID level is best for surveillance?
RAID 5 or SHR for four drives keeps three-quarters of the capacity and survives one failure; step to RAID 6 or SHR-2 at five or more drives so a second drive failing during a rebuild does not lose your footage. A UPS guards against unclean shutdowns mid-write.