DS-7608NI-I2/8P - 1 or 2 hard drives?

[milleniumaire]

Is there any advantage to installing 2 x 3TB hard drives rather than 1 x 6TB hard drive in the DS-7608NI-I2/8P NVR?

Is it clever enough to spread the recording/encoding load amongst the two drives or does it simply write to them in serial i.e. fill one drive first, then the other?

Thanks.

 

[fullboogie]

It writes to #1, then to #2. Buy the biggest ones that cover your needs.

 

[JB1970]

As @fullboogie says it'll fill the first, then the second then repeat so if you use two drives, only one of them will be use at a time as by default the NVR storage is in Quota Mode. Set to Group mode you're able to split the cameras and choose which cameras will record to each drive. I had an issue some time ago and set Group mode to allocate one drive to a couple of 8 megapixel cameras I had an issue with.

I thought about this myself some time ago. In the hard drive specifications there's a figure for how many Terabytes throughput per year the drive is rated at. Now my maths (math if you're stateside ) is probably way off, but using the Western Digital Purple as an example:

- 3TB is specified as 180TB per year
- 6TB is specified as 180TB per year

Based on that, surely two 3TB drives is better than one 6TB. Additionally you remove a single point of failure if one goes down.

 

[milleniumaire]

Thanks for your feedback @JB1970 and @fullboogie.

I was hoping the NVR might be clever enough to control 2 hard drives simultaneously and it seems that it does.

I agree with you @JB1970, you would expect 2 drives to be more resilient than a single drive, plus if the NVR has two HD controllers, surely this would improve performance when it comes to recording/encoding if you split the cameras between drives as you say. I assume you do this through the software.

Another advantage is that 2 x 3TB drives cost less than a single 6TB drive. It seems crazy that using twice the materials to build 2 HD's is cheaper than building a single HD, but I guess that's how the manufacturers make more money from selling larger capacity drives!

I'm potentially looking at 5 x 4MP cameras, so could allocate 2 cameras to one drive and the other 3 to the other drive.

It therefore sounds like a no-brainer to buy 2 x 3TB drives rather than 1 x 6TB drive as I can only see advantages!

 

[JB1970]

Thanks for your feedback @JB1970 and @fullboogie.

I was hoping the NVR might be clever enough to control 2 hard drives simultaneously and it seems that it does.

I agree with you @JB1970, you would expect 2 drives to be more resilient than a single drive, plus if the NVR has two HD controllers, surely this would improve performance when it comes to recording/encoding if you split the cameras between drives as you say. I assume you do this through the software.

Another advantage is that 2 x 3TB drives cost less than a single 6TB drive. It seems crazy that using twice the materials to build 2 HD's is cheaper than building a single HD, but I guess that's how the manufacturers make more money from selling larger capacity drives!

I'm potentially looking at 5 x 4MP cameras, so could allocate 2 cameras to one drive and the other 3 to the other drive.

It therefore sounds like a no-brainer to buy 2 x 3TB drives rather than 1 x 6TB drive as I can only see advantages!

Well you could do it either way. If you leave the storage set up in quota mode all of the cameras will record to disk 1, fill it, then move on to disk 2, then back to one when it begins to overwrite and so on. If you set it in group mode you can have both disks in action at the same time recording different cameras if that’s your preference. Keep in mind however that if you choose to do the latter, there’s still a single point of failure for a group of cameras if a disk fails. I’ve yet to have a complete failure of a drive in an NVR in the last seven or so years. Usually it’ll be a gradual breakdown with intermittent recording exceptions reported in the logs.