Large amount of "other" data, possible Hyper-V/duplication issue?

[DaveJ]

I'm running Server 2016 with the Essentials role. After a failed patch update this evening, I happened to check my Drivepool status and saw it shows 2TB of "Other" data on two drives. I've read the stickied article in the Nuts&Bolts forum, but I'm still confused as to where that data is located. I've confirmed that all of my data is in the pool, and tried remeasuring and rebalancing to no avail.

The only thing I can think of is the two drives in question store a 1TB Linux VM running on Hyper-V in a duplicated folder, which would account for the 2TB "other" data. Are there any issues with duplicating a Hyper-V VM in a pool?

 

[Shane]

Based on this thread I believe DrivePool isn't "measuring" the VM as duplicated or not while it's open for writing; if you stop the VM you should see it show up as Duplicated instead of Other. That thread also indicates that VMs should be fine when using (real-time) duplication.

[DaveJ]

Thanks for the quick reply. I can confirm that powering off the VM shows it as duplicated.

[Christopher (Drashna)]

Shane is stop on, as usual.

Any files that are open are usually "locked".  And when measuring, duplicating and balancing, StableBit DrivePool avoids locked files, since we can't ensure the state of these files while they are locked.  (which is part of why they get locked by the OS, in the first place, so nothing else can mess with them).

Once they're no longer locked, they should be fine, and should be updated during use.  Though resizing VHD files are ...tricky. And if you have the space, fixed sized VHDs would be better to use, if they're stored on the pool. 

[DaveJ]

2 hours ago, Christopher (Drashna) said:

Shane is stop on, as usual.

Any files that are open are usually "locked".  And when measuring, duplicating and balancing, StableBit DrivePool avoids locked files, since we can't ensure the state of these files while they are locked.  (which is part of why they get locked by the OS, in the first place, so nothing else can mess with them).

Once they're no longer locked, they should be fine, and should be updated during use.  Though resizing VHD files are ...tricky. And if you have the space, fixed sized VHDs would be better to use, if they're stored on the pool. 

Noted! I'm actually using a fixed size VHD. I've already resized it once and had no issues - is there anything I should be aware of?

[Christopher (Drashna)]

Fixed sized is good.  Other than needing to fit on the underlying drives, it should be fine.