Ask Your Question

Disk scheduler of VM instance.

asked 2016-10-04 01:02:01 -0500

syko gravatar image

The host machine and the instance both use Cent OS 7 (3.10.0-327.10.1.el7.x86_64). VM uses KVM.

I checked the io scheduler of VM instance as follows:

cat /sys/block/vdb/queue/scheduler

It gives "none" (which is not the case for the host machine)

Does it mean that VM instance has no control over the disk io scheduling?

edit retag flag offensive close merge delete

1 answer

Sort by ยป oldest newest most voted

answered 2016-10-04 13:46:14 -0500

This is correct - this isn't implicity saying the VM has no control, it's simply saying that it doesn't make sense to run an elevator on virtual devices.

Instead, the I/O is passed straight down the stack to the real disk where there is a single elevator managing all I/O to that disk, whether it comes from different virtual machines, or logical volumes. In your case, this means that the scheduler on the host machine is the one that's being used for that device.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Get to know Ask OpenStack

Resources for moderators

Question Tools

1 follower


Asked: 2016-10-04 01:02:01 -0500

Seen: 95 times

Last updated: Oct 04 '16