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jh75's avatar
jh75
Aspirant
Nov 08, 2016
Solved

Adding 4TB - total storage volume not increased

Hi,

We have a Readynas nv+ v2 used for backing up to. It has 4x2TB hdd’s.  The NAS has run out of space and I am in process of adding 2 new 4TB drives.

I am adding one drive at the time and have only added 1 drives so far. After adding 1x 4TB drive the storage ‘size’ has not increased – it seems that only 2TB of the new drive is used.

I can see in the admin section (under info) that the 4TB (3726GB)  is recognised.

 

Before adding the second 4TB drive I want to make sure this work.

Any idea how expand the storage over all drives?

 

Thanks

JH


  • jh75 wrote:

     

    I am adding one drive at the time and have only added 1 drives so far. After adding 1x 4TB drive the storage ‘size’ has not increased – it seems that only 2TB of the new drive is used.

     


    This is normal.  The system can't use the full drive space without sacrificing RAID redundancy.

     

    When you add the second disk there will be a second resync and the volume will expand by 2 TB.  You likely will be prompted to reboot the NAS half-way through that resync

12 Replies

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  • StephenB's avatar
    StephenB
    Guru - Experienced User

    jh75 wrote:

     

    I am adding one drive at the time and have only added 1 drives so far. After adding 1x 4TB drive the storage ‘size’ has not increased – it seems that only 2TB of the new drive is used.

     


    This is normal.  The system can't use the full drive space without sacrificing RAID redundancy.

     

    When you add the second disk there will be a second resync and the volume will expand by 2 TB.  You likely will be prompted to reboot the NAS half-way through that resync

    • jh75's avatar
      jh75
      Aspirant

      Thanks,

       When adding the next 4TB drive it expanded across as expected.

       

      j

    • JBDragon1's avatar
      JBDragon1
      Virtuoso

      You can see this looking at the HDD storage space Calculator.

      http://rdconfigurator.netgear.com/raid/index.html

       

      Just drag a drop the HDD's and you can see how much space you get on the right.  Play around with things.

      So you start out with 5.43 TB of Space with 1.82 TB used for protection.  That's how much storage space a 2TB HDD works out to.  When you add a single 4TB HDD, you are basically wasting 1.82 TB of space.  Think about it as Data is spread out though the 4 HDD's.  With one twice as large. there's no other HDD what enough space, equal amount of space where if one dies, the other one can cover it.

       

      Once you add a second 4TB HDD, you now get 7.25TB of space, and 3.64TB used for protection.  3.64 is the amount of storage space on a 4TB HDD.    I know, you're thinking you should get like 4TB of space right?  But your total gain is only about 2TB.  Once you get to the 4th, you end up with 10.9TB.

       

      I happen to have 13.62TB of space from 6 3TB HDD's.  At some point I plan to switch them out to 6TB HDD's.  That would boost me up to 27.2TB of space.  Or doubling what I currantly have.  Losing storage space for Redundancy is worth it.   It's still no BACKUP!!!  You're NAS could break down, or it gets stolen or you have a fire, etc.  Things happens.  If 2 HDD's take a dump on you at the same time and it can happen as rebulding the new HDD really works the other HDD's hard.  In general the HDD's may be around the same age, and a second HDD takes a dump in the middle of a rebuild and there goes your data!!!!  it takes HOURS to rebuild a new HDD.  Larger it is, the longer it's going to take.  Don't count on a NAS to save your Data!!!  

      • StephenB's avatar
        StephenB
        Guru - Experienced User

        JBDragon1 wrote:

        You can see this looking at the HDD storage space Calculator.

        http://rdconfigurator.netgear.com/raid/index.html

         

         


        Alternatively, for the default XRAID you can sum the disks and subtract the largest.  That will give you the results in TB (see below).


        JBDragon1 wrote:

         3.64 is the amount of storage space on a 4TB HDD.


        To explain this a bit more fully - there are two units of measure here.  The disk drive is 4 TB. 1 TB = 1000*1000*1000*1000 bytes.  3.64 is what the NAS volume will show, because it is using TiB, not TB.  1 TiB = 1024*1024*1024*1024 bytes - about 10% bigger than 1 TB.  Unfortunately the NAS (like Windows) labels the size as TB or GB - even though it is really TiB or GiB. 


        JBDragon1 wrote:

         Losing storage space for Redundancy is worth it.   It's still no BACKUP!!! ... Don't count on a NAS to save your Data!!!  


        Totally agree here.  RAID is simply not enough to keep your data safe - for all the reasons you mention.  Unfortunately a lot of people discover this the hard way.

         

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