I have a server in my office to run several dev virtual machines. It runs Windows Server 2012R2 with Hyper-V and Storage Spaces. There are 5 HDDs combined in one storage pool and virtual disk above that pool
- Layout = Mirror
- Physical disc redundancy = 1
(every chunk is stored on 2 random disks)
Recently my virtual machines become somewhat slow, a clear sign that disk is about to fail, but which one?
Storage Spaces
On a picture below I already retied PhysicalDisk5 but Storage Spaces thinks the disk is perfectly fine.
Disk properties indicate no issues.
PowerShell
Get-PhysicalDisk | Select-Object -Property FriendlyName, DeviceID, SerialNumber, Model
Get-PhysicalDisk | Select-Object -Property *
Get-PhysicalDisk | Select-Object -first 1 | Select-Object -Property *
Powershell does not show any useful info too
Solution
The solution was to use HDSentinel (or probably any other disk tool that can read bad sectors count) There is a portable 30 day trial version of it, so you can solve rare disk problems like that without extra cost: https://www.hdsentinel.com/download.php
What to do
If all virtual disks are healthy you are fine.
- get disk model and serial number
Get-PhysicalDisk | Select-Object -Property FriendlyName, DeviceID, SerialNumber, Model
- turn server off and unplug bad disk
- put new disk. New disk must have the same or greater capacity.
- in storage spaces try to delete "lost communication" disk and choose the new one
If your pool is already Degraded you need to be gentle and careful.
- Using PowerShell mark disk as retired
- Right click disk on storage spaces physical disks and try remove it.
- If remove was successful repair all virtual disks first.
If not - there is not enough free space to move data outside of your disk. If all SATA sockets are occupied and you cannot insert new disk - you are stuck. You need to move away all data and recreate virtual disk :(
- Unplug bad disk and replace it with new one
Final thoughts
I will never use Physical disc redundancy = 1 again. Relying on a fact that only one disk will fail is not enough. In my case one disk failed and other was full of bad blocks. I was able to be patient and let the disk copy its data outside veeeery slowly. It took a week, no kidding. But next time I might not be that lucky.