Why do we suggest using raw disks instead of qcow2 images?

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swordlink1
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Why do we suggest using raw disks instead of qcow2 images?

Post by swordlink1 »

qcow2 images are dymanically-expanding, instead of pre-allocating all the space at once, which allows to save space.
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swordlink1
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Re: Why do we suggest using raw disks instead of qcow2 images?

Post by swordlink1 »

I see why now...
Image
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adespoton
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Re: Why do we suggest using raw disks instead of qcow2 images?

Post by adespoton »

QCOW2 is a great format in that you can keep it sparse, and with the -c flag you can even compress the blocks.
Another benefit is that you can snapshot an image that uses the QCOW2 format.
Unfortunately, because it's copy-on-write, it also can become corrupted, especially when combined with a virtual NVMe controller and disk caching. QEMU is really stable with raw image formats, but you do risk losing the image if you're using QCOW2 and something goes wrong.
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