Forum Discussion

Apprentice

Aug 15, 2015

HDD price

Hi all, slightly OT conversation here. I purchased 2xWD RED 4TB HDDs last summer for my Pro 6. The idea was to add another 4TB HDD once the price had fallen. I have been monitoring the prices, ...

Hard Disk

tony359

Apprentice

Aug 17, 2015

Thanks for your contribution.

I did not realise we had reached the maximum storage capacity of perpendicular recording.

Oh well, this explains why the 4TB HDDs have been holding their price for a while.

I have plenty of empty bays on my NAS, I currently have 2x4TB. Would you buy a 5 or 6TB HDD for future expansion (can I use the extra space if I factory reset the unit?) or would you stay on 4TB confident that by the time the NAS is full, something new has come up on the market?

Thanks

Antonio

StephenB

Guru - Experienced User

Aug 17, 2015

OS 4 has two expansion limits - a volume cannot expand over 16 TiB, and it cannot grow more than 8 TiB larger than its starting point. You cannot install mixed disk sizes with a total volume > 16 TiB, because the xraid2 won't vertically expand when it creates the initial volume.

If you are needing more space now, I'd get another 4 TB drive - that will double your volume size, and is cheaper (per gigabyte) then the larger disks right now.

Later on (when you are faced with a factory reset anyway) you can perhaps migrate to OS6 - which doesn't have those expansion limits.

tony359
Apprentice
Aug 17, 2015
Thanks Stephen,

Sounds good.

I tried OS6 in the past and I felt it was a little young. As you say by the time I need extra space - and I'm faced with a factory reset anyway - I may want to move to OS6 and install whatever the market offers in the future.

Thanks for your advice as usual.
- StephenB
  Guru - Experienced User
  Aug 17, 2015
  Another article on HDD pricing... http://www.forbes.com/sites/tomcoughlin/2014/12/22/hdd-areal-density-and-tb-trends/
  
  The first figure shows that current hard drives are essentially at the 1 terabit/sq inch ceiling of PMR. It predicts introduction of HAMR in 2017.
  
  The article also discusses the possible impact on pricing of both industry consolidation and the loss of factories in Thailand in late 2011. The pricing trend shift to a new track in 2012 as you can see by the graph in figure 2.
  - ukbobboy
    Luminary
    Oct 11, 2015
    Dear Forum Members
    
    I know that this is an old thread and I have nothing technical to add but as anyone noticed that the price per TB for an HD goes up the bigger the HD capacity.
    
    For example, the price per TB for a 4TB WD Red is about £31.50 but for 3TB WD Red is £21.23, more than £10 less.
    
    My calculation is rough and ready and cannot be taken as a definate state of current affairs but is anyone as surprised as I am that 4TB HD prices have not started to fall yet. There are probably various economic and (possibly) environmental issues that have kept prices high but I feel, rather than know, that HD prices should have started to fall by now.
    
    UK Bob