Very low disk performance

[karateo]

Hi!

I have tried WIN10, WIN7, Debian latest x64 and I got with all very low disk performance.

Updating, opening apps, navigating through OS etc.

 

I don't have a CACHE so my virtualdisk is stored in parity.

I use BTRFS and the user share which has the virtualdisks has copy on write enabled.

 

1) Should I disable copy on write? (basically create a new share with disabled cow and move files there)

2) Should I expect big performance improvement or a cache drive is the only way?

 

(One question I just thought of. Should I disable cow for the user share I store active torrents?)

[itimpi]

If you do not have the VM hosted on a drive that is not part of the data array (i.e. cache drive or drive not controlled by uNRAID) you are going to get bad performance.  The architecture of unRAID means it always takes a big hit on write performance so the parity protected array is not very suitable for acting as a system drive for an OS in a VM.

 

According to the KVM documentation you do not want to have a .qcow2 virtual disk hosted on a BTRFS file system as this is known to adversely affect performance.  If you need to run this way then using a raw image (.img) is likely to perform better.  You may also find you get better performance if the image is not in a user share but at the top level of a disk share.

 

However at the end of the day you will only get good performance if the VMs virtual disk is not hosted on the parity protected array.

[karateo]

Thanks for the clarification!

I already moved all files in a non cow folder (/mnt/disk1/Virtualizationfiles/) and I am going to look for a ssd to act as cache or non-array disk.

 

Any idea about the torrent files?

[itimpi]

Thanks for the clarification!

I already moved all files in a non cow folder (/mnt/disk1/Virtualizationfiles/) and I am going to look for a ssd to act as cache or non-array disk.

 

Any idea about the torrent files?

No idea about the torrent files.  If you go the route of a SSD you may want to initially download the torrents to there and later move them to the array?  Worth thinking about this when deciding what SSD size is appropriate for your needs.