[Solved] All 2TB Reds or 4TB parity+2TB Reds?


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I'm about ready to purchase a majority of my new build and can't decide between 2 or 4TB drives. Once I fill all 20 data bays up with reds in a norco 4224 it'll be around 36-38TB of space. The other 4 slots will be a warm spare, docker, cache, parity. Since I only plan to buy one drive bi-weekly (paycheck) does it make sense to stick with 2TB drives for <$100 or spend almost twice as much on twice the storage if it'll take me a long time to fill up the bays? If it helps this will be a 24/7 server too.

 

 

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Personally, I'd go with the larger drives using less space but never overbuy. If you have enough free space for your files to be organized how you want, there's no need to buy a drive to sit there not being used.

 

A nice benefit I saw of going with the newer 4TB drives is actually having faster parity checks and rebuilds than using the older slower 2TB drives.

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A nice benefit I saw of going with the newer 4TB drives is actually having faster parity checks and rebuilds than using the older slower 2TB drives.

 

Suspicious of this claim. Although the 2T drives may be slower, the parity check would only be going from 0-2T instead of 0-4T. The 4T would have to be twice as fast which I think is unlikely.

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A nice benefit I saw of going with the newer 4TB drives is actually having faster parity checks and rebuilds than using the older slower 2TB drives.

 

Suspicious of this claim. Although the 2T drives may be slower, the parity check would only be going from 0-2T instead of 0-4T. The 4T would have to be twice as fast which I think is unlikely.

 

Of course in addition to the data density increase I also switched from having 8 data drives of 5 to 6 year old 2TB WD Greens to only 4 data drives of new 4TB HGST 7200rpm. The old parity check speed average was 70-72 MB/s, the new is 131-140 MB/s.

 

So not exactly twice as fast, but almost!

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A nice benefit I saw of going with the newer 4TB drives is actually having faster parity checks and rebuilds than using the older slower 2TB drives.

 

Suspicious of this claim. Although the 2T drives may be slower, the parity check would only be going from 0-2T instead of 0-4T. The 4T would have to be twice as fast which I think is unlikely.

 

Actually, the claim is accurate, BUT misleading.  If you indeed use the "... older 2TB drives" [e.g. WD20EADS and WD20EARS], they can indeed take as long or even longer for parity checks than new 1TB/platter 4TB units, as the drives have much lower areal density.    Some won't be quite as long, as there were both 500GB and 667GB platters used in the EARS models (i.e. some had 3 platters, some 4).

 

HOWEVER ... the current 2TB drives -- WD20EZRZ Green units and WD Reds -- have 1TB platters => i.e. the same areal density as the 4TB units.    Parity checks on these will be much faster than 4TB units.

 

Bottom line:  If you're buying NEW drives, parity checks will be much faster with 2TB drives than with 4TB drives (about half the time).    HOWEVER ... I'd still buy 4TB drives, as this will give you twice the potential capacity for your system, and the only extra cost is the extra cost for the parity drive => in fact, you'll save some of that extra cost as you buy the data drives, as the 4TB units are generally a bit less than twice the cost of a 2TB unit of the same series [this is true for both the WD Greens and the WD Reds; and for the HGST DeskStar units]

 

 

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