Question Backup drives

Jan 26, 2023
I need some advice here.

I am in the process of building a new (personal) backup machine. I intend to use 8 x 3.5 inch drives with a minimum capacity of 8 TB per drive. These 8 drives will be used to form a single ZFS raidz-2 volume.

The way I indent to use that system is to start it 1 or 2 times a week, run a backup from all my devices, maybe do some additional stuff, like software upgrades, and then shut it down again. So it only runs for a few hours per week. Meaning I don't exactly need 24h-rated drives. However, beyond 8 TB capacity per drive, there doesn't seem to be anything normal/non-enterprise. Which means, if I choose to select larger drives (>8 TB), they will be 24h-rated anyway. And since the system is only running when I do the backups, the noise from the drives or even power consumption is not a very big concern.

In terms of price per TB, these are (currently) my best 3 options:

  • Seagate Exos X18 16TB
  • Seagate Exos X18 16TB
  • Seagate BarraCuda 8TB
Capacity-wise, the 8 TB drives will provide me a net capacity of ~48 TB. For the planned lifetime of that system for at least 5 years, the 48 TB might be a tight fit, so I actually tend to prefer more capacity.

My main concern here is that I don't know how those enterprise drives, like Seagate Exos X, are going to handle the weekly start/stop cycles (50-100 per year). Is that something I need to consider or be concerned about? Or do these enterprise drives just don't care about that, even since they are supposed to run constantly?

So basically, the question is: Exos or BarraCuda? Can the 24h-rated enterprise drives (Exos X) operate well in this scenario or should I rather stick to the non-enterprise BarraCuda drives?
Prepare for significant speculation unless you can track down a semi-accurate study of longevity/reliability of those specific drives at those specific capacities.

How much speculation are you willing to accept?

How much reliance are you willing to put on anecdotes?

Someone like Backblaze may have some info, but I wouldn't count on it.


Mar 11, 2022
For drives that will only be powered up once or twice a week, I don't think it matters. I mean, a BarraCuda, for example, can run 6+ years in a normal PC being powered on every day. I don't know about the Exos drives since I never had one, but I personally wouldn't worry too much about it honestly.


Mar 16, 2013
For the singular items on your desk, lifespan/reliability predictions are pretty useless.
Those numbers only count in large numbers.

Your use case is nothing exception or hazardous.
Your particular drive(s) will likely last a long time.

But, this is one of the reasons for backups in depth.
3 copies, on at least 2 different media, at least one offsite or otherwise unavailable.

It is HIGHLY unlikely all these copies would go bad at the same time.