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4TB Drives are being displayed as 2TB each


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Hi Xpenologist,

I bought 2x4TB WD Red NAS drives for and added them in my DS3615xs (HP Z800 :P) but as I am using MBR version of loader System is telling me each drive is 2TB only.


did a little search on this and found that its due to MBR and max size is 2TB only.


Any way/workaround to fix this? 


Thanks and Regards


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the z800 seem so have a intergated sas controller and from what i found and your symptoms its LSI SAS 1068E that has a hardware limit of 2.4TB for a disk, nothing you can do about it then using another controller like lsi sas 9211-8i and its clones (in IT mode) or a ahci sata controller (a two lane 88se9230 or a jmb585 would be working too, as its presumably only pcie 2.0 a one labe controller like 89se9215 would not be that good as it would only have max. 500MB/s on the one pcie lane)

9211-8i can have 8 sata ports and 8 pcie lanes and might be a good choice it its planned to be extended beyond sata 4 ports

(edit: if there are normal sata onboard from the chipset you could use them instead the sas ports and you might not need anything additional for you two disks)

Edited by IG-88
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I used removed to drives from SAS ports and plugged them in SATA port I can see the these are 3.67TB capacity drives but now DSM is not letting me create the volume.

System failed to create [Storage Pool 2](Device Type is [RAID 1]) with disk [Drive 2, Drive 3].


I tried to create storage pool with just one drive still the same 


System failed to create [Storage Pool 2](Device Type is [Basic]) with disk [Drive 2].

Edited by AbuMoosa
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  • 2 weeks later...
5 minutes ago, bearcat said:

@AbuMoosa You should not be using HW Raid, but leave it up to DSM to make a software Raid.

In your BIOS, the drives *should* be configured as single drives, AHCI mode.

I know but DSM wouldn't let me configure these drives in raid config or was not even letting me use them standalone, see my post above.
I had to go this way as my HP Z800 was displaying these two as non raid drives (while booting). As soon as I configured them in raid in BIOS everything worked like a charm and DSM happily let me put those drives in a raid 1 config which was what I wanted :) 

Edited by AbuMoosa
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