[Question]: Hi, Why not use the QCOW2 format for the hard disk by default to save space ?

[mike37510]

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Question

Hi, Why not use the QCOW2 format for the hard disk by default to save space ?

[NateChoe1]

I'm the contributor who added qcow2 support in this commit. I made the DISK_FMT variable so that old docker-compose configs that used raw images would still work, even though qcow2 images would save space. There is already code to convert between disk formats, so theoretically changing the default could be done seamlessly. I've submitted PR #575 to do this, although there might be some technical reasons to have raw images as the default that I just don't know about.

[kroese]

@NateChoe1 I use this project as the base for https://github.com/dockur/windows and when using the QCOW2 format, some users reported strange error messages during the installation of Windows. When they switched to RAW suddenly their problems disappeared.

It might be a specific combination of circumstances, because all those reports were from Unraid users. So maybe its the combination of using the QCOW format when the host filesystem is zfs or btrfs, or some specific kernel version, etc.

But just to be sure I reverted the default back to RAW, until I know what is going on.

[mike37510]

ok, thanks, I understand better now.
Thank you for your answers.