Samsung PM981 not showing up with full capacity in Windows

alex_stief

Active Member
May 31, 2016
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I have a weird issue with a Samsung PM981 m.2 NVMe SSD. It's used, came with a workstation I bought.

In the bios/UEFI, the drive shows up as 1TB. As it should, the label says it's a 1TB version, and the seller (who used windows exclusively) claimed the same.
In Windows, the drive only shows up as a 512GB version. Disk partitioner and tools like Crystaldiskinfo see is as a 512GB drive, but with a model number "MZVLB1T0HALR". Which is indeed the 1TB version.
Booting up Linux, it gets super weird. nvme list shows the correct drive, with a capacity of ~1TB. I used fdisk and mkfs to create a new NTFS partition with default settings. Which defaulted to ~1TB. The process finished without errors.
Booting up windows again, disk partitioner does not recognize this new partition. Instead, it still shows the drive with 512GB of unpartitioned total capacity.

What the hell is going on here? And what could I do to get the full capacity usable in windows?

By the way, according to SMART values, the drive has only seen 288 hours and 9TB written, with no errors logged.
 

i386

Well-Known Member
Mar 18, 2016
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Start diskpart, select the proper device and look at the volumes.

I had a 200 GByte HUSMM ssd that showed up as a 14.5TByte device in diskmanagement :D
(deleting the volumes on that ssd helped to fix that problem)
 
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alex_stief

Active Member
May 31, 2016
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Thanks for the quick suggestion. However, after deleting all existing partitions in Linux once more, the SSD now shows up as 1TB in Windows too. I also verified with diskpart, so your effort was not in vain, and I learned something new ;)
 

JSchuricht

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Apr 4, 2011
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Too late now but i386 has you on the right track for the future. Diskpart, list disk, select disk, then clean. I usually see the small partition issue on USB drives after they had a linux partition them but I have also seen the weird oversize partition after a drive was part of a RAID array.