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wicked1980's avatar
wicked1980
Aspirant
Jan 20, 2016

ReadyNAS NV+ v2 with 4 4TB drives in raid5 showing 10TB volume

I got 4 new 4TB harddrives (wd green).

 

Did a factory reset with the new drives installed and used RAIDar to configure them in RAID5.

 

One volume is automatically created with a capacity of 10TB. Not the expected 12 TB

 

Do I have to expand the volume after the Sync proces is complete (Disk 4 is syncing)?

4 Replies

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  • StephenB's avatar
    StephenB
    Guru - Experienced User

    The NAS will report the volume size in TiB (1024*1024*1024*1024 bytes) not TB (1000*1000*1000*1000).

     

    So you should be seeing  about 10.9 TB on the dashboard. 12*(1000/1024)*(1000/1024)*(1000/1024)*(1000/1024) = 10.91.

  • Correct. But that does not account for the missing 2 tb (give or take)

    4 x 4 tb in RAID5 = 12288 gb due to parity
    • mdgm-ntgr's avatar
      mdgm-ntgr
      NETGEAR Employee Retired

      10.91TB rounded down is 10TB.

       

      StephenB already explained that like most computers we use a different measurement to disk manufacturers.

      It's a bit like whether you measure distance in kilometres or miles. You may get a different number for the distance from A to B, but the distance is still the same.

      Whether you use base 10 or base 2 for measuring space on a data volume makes a significant difference to the number you get.

       

      Using TB (uses base 10) you would get (4-1)*4 = 12TB = 12288GB.

       

      12*(1000)^4/1024^4=10.91. 12TB=10.91TiB. It's still the same amount of space, just a different way of measuring it. Like most computers we use TiB (uses base 2) but call it TB. This can get a bit confusing as disk manufacturers use TB (base 10), but it's the way it's always been as far as I can remember.

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