Hi Ravuth, Im not a security cam expert but I am Storage Engineer and can get you closer to your question. Like most things in IT "It Depends" on your needs. CVR is cloud based storage, advantages would be it's stored offsite and you don't have to supply hardware specifically for it. But the "cloud" is just someone elses computer and you will need to pay for that. NAS is Network Attached Storage, think of it as file based storage and shared or shareable, this is the more common method for most smaller home users. Think departmental shares at work and home directories, large repositories where you would want many devices or people to be able to read/write to a single location without any other dependencies. This will be SMB for windows machines, NFS for unix machines on the AFS for mac but macs can translate and mount via SMB and NFS but it's slower for them. SAN is a storage area network, there are poor man versions of this called iSCSI but it's dependent on a Ethernet connection and typically not a good solution for production level things so Im only going to address what is typically considered SAN. It's block based meaning the systems connecting to it will own and control the disks assigned to it at the block level which means it will be locked to the OS connecting to it. The advantages are it's not shared with other devices or users at the SAN level if the system owning the SAN disks wants to share it they can but then you just turned your SAN into a NAS. SAN is used for intensive applications like Databases and Exchange servers etc.
So my un professional view of where surveillance is going I would venture to guess it's probably cloud for many so they can sell you a subscription and also get your meta data. Not always a bad thing unless your into privacy and security. I think Ring is going a descent job of mainstreaming cloud storage and the security industry which would be considered cloud and Im sure there are lots more out there. Me, I have a ring
doorbell and love it but I also have my own NVR and my own NAS, they all have their place and I can use one to backup the others etc. I personally don't see a use for SAN storage in the surveillance realm. For video and probably used for modern clouds is most likely
object based storage . Which I haven't worked with much but I have moved data of those systems onto NAS.
James
