Hi there!

New user hoping for some help as i can't seem to find anything online.

I have a 4TB red, one of 4 in my NAS. This one's less than 2 months old and was dropped from the array as failed a smart test. Validated that and looked at using WD's Lifeguard tool to do an extended test and attempt to fix.

I ran into problems running their utility on Win10 there seems to be some sort of issue with it. So i installed it on an old WinXP machine and its was able to recognise the drive. GTG i thought...

This went well and errors were found and fixed. A second extended test was run and nothing came back bad so all set. Popped the drive out and put back in the Win 10 machine and wiped all the partitions to force the NAS to rebuilt. Did right from Disk Mgmt.

Weird thing was the NAS wouldn't mount the disk for a rebuild. It wasn't until i saw the size as 2.7TB i realized something was going on. I've put it back in the Win 10 and XP machine and same thing in both. Looking closer at the Lifeguard apps registry it shows there as a "3000GB" drive.

I can only assume the Lifeguard app made some sort of change?

Disk mgmt only shows one unallocated GPT partition of the reduced size and thats it. Are there any thoughts as to what caused the full capacity to be none recognizable?

Could this be the problem?

GigaByte BIOS bug results in loss of 1TB capacity:
http://www.hddoracle.com/viewtopic.php?f=59&t=150&p=275

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A backup a day keeps DR away.

Hi fzabkar! I'm at work but I'm fairly certain it is a GigaByte board in that old XP machine! I did goof when I was attaching it as I pulled the main drive rather than one of the data drives [I needed to steal power and a SATA cable as the case is full] which would fit "nicely" into the scenario described in your link.

Well I seriously hope that it is indeed a 1TB HPA partition that's been snuck onto the drive, if so you have my most profound thanks as I was completely stumped.

I'm looking through the tool list on your link and most require booting off a bootable CD or USB to fix the issue. This one seems to be a little more friendly, does anyone have any experience with Atola? http://blog.atola.com/restoring-factory ... -capacity/

Whelp! That definitely seemed to be it - sheesh!

I used the Atola tool, which although refused to work on Windows 10 was fine on the XP box. Capacity back to 4TB and running it through another WD Lifeguard extended test.

Many thanks again - wouldn't have gotten this figured out without the help here!