Increasing EBS Volume disk size created a 3rd drive on Windows Disk Management

Question

I have 2 EBS storage volumes attached to a Windows EC2 instance.  The volumes were 40gb and 100gb.  I increased the 100gb disk to 300 gb, and RDP'ed to the EC2 Windows box ran disk management to allocate the new space to the D drive, but this is what I found instead:

https://pasteboard.co/swhXG4lEqQDA.png

It shows a new drive W that isn't formatted, but has 200gb unallocated to it.  Now if I look at the total amount of space available I'd have 40gb (C:/) + 100gb (D:/) + 300gb (W:/)= 440gb!?  But in the AWS console I show only 340gb total between 2 EBS volumes.  Which brings up the issue that if I format the disk I might be overwriting data because there isn't 440gb allocated.  I've tried rebooting the box without success it still shows this extra drive.  And I can't find any information about this situation or how to fix it.

Neha_R · Answer

Hello,

Thanks for your post. If the instance type supports instance store volume then it is possible that 3rd drive is "Instance store" [1] volume. You can verify instance type information here [2].
- [1] https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html
- [2] https://aws.amazon.com/ec2/instance-types/

To verify the exact issue, I will request you to open a support case with the resource detail. 
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html

Increasing EBS Volume disk size created a 3rd drive on Windows Disk Management

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