4x 4TB or 3x 6TB

[eric.frederich]

Each configuration with a single parity would end me up with 12TB storage correct?

 

Getting 4x 6 TB would be a bit cheaper but possibly use more power?

 

What other pros/cons are there?

Performance?

Stability?

Future expansion implications?

[1812]

compare read/write speed between the 4 and 6 tb drives.

 

depending on your setup, the 3x6 may take long to complete parity checks.

 

 

[SSD]

Generally I'd advise larger is better. It means you can add more drives before having to swap out a smaller drive for a larger one to add storage.

 

Larger drives often are cheaper per tb, an important metric for me.

 

The 8T Seagate archive drive is something you might want to consider. A reliable and inexpensive disk ($25/TB), especially if you don't mind removing it from an external packaging (see my post in good deals), it can be had cheaper than most 6TB drives. I'd recommend those. Good experiences by unRaiders.

 

I've recently bought some to retire some older drives and very happy with them. These are the current sweet spot of drive sizes. Three of these would cost just under $600 and give you 16TB of usable space, and ability to continue adding more 8TB drives cheaply.

 

UPDATE: Saw 1812's comments. And he is right, but I wouldn't let either factor impact a buying decision. Parity checking is a once a month operation. Larger drives take longer, as do systems with multiple drive sizes. And an array of 8T drives will be faster than an array mixed, for example, with 4T and 8T drives. I think it's a little unfortunate that parity check times are a convenient way of comparing performance.

 

Related to individual drive speeds, if your looking for high performance, unRaid may not be for you. Any drives you look at are fast enough to saturate a gigabit lan.

 

I would reconvene an SSD cache.

 

My $0.02.

[eric.frederich]

Let's say I get 3x 8TB drives, I can add another 8TB drive later without having to shuffle all the data for it to be spread evenly?

How does that work?

 

Also, I was looking at HSGT drives because the stats published by BackBlaze seem to show they're the best.

 

I'll have to look at that post and see what the external packaging is all about.  Can you re-use it with a different drive to make it a generic external enclosure?

[1812]

unRaid uses xfs and doesn't stripe data across drives. So you can add drives with essentially no downtime. There are benefits and drawbacks to this way of handling data.

[SSD]

1 hour ago, eric.frederich said:

Let's say I get 3x 8TB drives, I can add another 8TB drive later without having to shuffle all the data for it to be spread evenly?

How does that work?

 

Also, I was looking at HSGT drives because the stats published by BackBlaze seem to show they're the best.

 

I'll have to look at that post and see what the external packaging is all about.  Can you re-use it with a different drive to make it a generic external enclosure?

 

If you are adding a disk that is the same size or smaller than parity, you can add it, no muss no fuss. (Any new disk should be precleared before use). If you are adding a drive larger than parity, you need to upsize your parity and then add the old parity disk as a data disk. Neither are difficult or require data migrations.