OpenStack Compute (nova)

How do I run more instances than 256 when the number of loop devices is limited?

Asked by bastichelaar

I am running:

- Diablo 4
- LXC hypervisor
- No qcow images, just plain

Nova creates a loopback device for each instance. How do I run more than 256 instances when this is limited to 256? Is there a way to avoid having loop devices for the filesystem?

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Brian Lamar (blamar) said : 		#1

If you switch to using qcow images you'll automatically switch to using NBD instead of loopback devices for mounting images. That flags is use_cow_images=True. If you can't use that then another option is increasing the maximum number of loopback devices which can be made.

Normally this can be done, if you're using loopback support via a kernel module, by doing:

$ rmmod loop
$ modprobe loop max_loop=1024

Hope this helps!

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