Re: qemu-img convert is TOO slow

[Supratim Sanyal]

On 4/24/2023 7:11 PM, Zenaan Harkness wrote:
> If the filesystem has been used for a while, there may be many
> "deleted" sectors which are not zeroed?
>
> Some type of fsck (or nowadays possibly "trim") can zero all unused
> sectors of the image, before conversion?

I use zerofree, or simply dd if=/dev/zero of=/tmp/zero.zero 
bs=4096;sync;sync;sync;rm -fv /tmp/zero.zero - some variation of this is 
probably applicable to your case depending on your mount points and 
blocksize.