RAID drive sizes - when to migrate from 2TB? (your opinion)

[Lapsio]

Hello. I have 5x Seagate NAS 2tb RAID6 array in Linux storage server. However as I ran out of space I'm planning to upgrade it by adding another 3 drives. Unfortunately I noticed that 2TB drives are slowly becoming not optimal solution price-wise. So I started to wonder - when and if should I migrate to bigger drives.

My choice was initially influenced by IBM whitepaper which recommended using 2TB or smaller HDDs for important data in RAID arrays due to higher fault rate of bigger HDDs and bitrot. Also I started initially from 3 drives as I didn't have much money to start, so 2TB seemed to be good enough 5 years ago. Now as array grows I see people using 4 or 6 TB drives in NAS. And I'm a bit confused and unsure if my decision was wrong or it just became obsolete now and if I should do something about it.

I'm using JBOD and software btrfs RAID with encryption and SSD caching. Realistically i could scale up to 12 drives because that's what my old motherboard supports (including 2 pcie x1 controllers) and I want to dedicate this machine for storage and audio servers anyways. But I'm not sure if it makes sense to stick with 2TB drives or should I start migration now. What would you do in my place?

 

[rkzhao]

Budget and use are factors to consider. 4-6TB HDDs today are essentially the 2TB drives of 5 years ago as far as where they lie in the storage market so it's more just the evolution of the times. However, given the HDD industry shift towards more focus on just areal density and high capacity drives rather than high performance, the idea of higher fault rates in higher capacity drives is somewhat questionable, at least in the current market. Manufacturers put some the most advanced reliability features and best components into their largest capacity drives. I believe we're at 10-12TB on the top end for now and the projected growth is something like 20TB by 2020.

The middle capacity drives tends to be the most popular mostly for price reasons. As time goes on though, the size of media files and society's needs for storage grows along with the technology so that capacity point will always be growing. A couple years ago, the most popular capacity for general data servers was probably 3-4TB drives. Now, it's more like 6-8TB drives.

From a manufacturer's perspective, enterprise class drives are really only designed around a service life of 5 years. Client drives are 2-3 years.

So with all that, if it's for commercial use, certainly look into upgrading. For personal use, well, that depends more on you. I would still lean towards upgrading and I would look at 6TB more than 4TB but money is of course always a concern.

 

[the nerd 389]

You mentioned that you use a RAID 6 array. If that's the case, you don't have much to worry about, as even with an error on a single drive, newer rebuilding algorithms allow that kind of error correction as it's rebuilding. In older systems, an error like that would force you to restart the build/verification process.

You should be good with 5 x 6 TB drives using a modern implementation of RAID 6.

For reference, I use a 6 x 6 TB setup with four drives in RAID 6, and two hot spares. I've rebuilt the array several times now (mostly due to configuration changes/beginner mistakes when I was new to this sort of thing), and I've never encountered an issue during rebuilds.