[openstack-dev] [nova] bp proposal: libvirt-resize-disk-down

Jon Bernard jbernard at tuxion.com
Thu Jan 30 15:48:54 UTC 2014


* sahid <sahid.ferdjaoui at cloudwatt.com> wrote:
>   Greetings,
> 
> A blueprint is being discussed about the disk resize down feature of libvirt driver.
>   https://blueprints.launchpad.net/nova/+spec/libvirt-resize-disk-down
> 
> The current implementation does not handle disk resize down and just skips the
> step during a resize down of the instance. I'm really convinced we can implement 
> this feature by using the good job of disk resize down of the driver xenapi.

In case it hasn't been considered yet, shrinking a filesystem can result
in terrible fragmentation.  The block allocator in resize2fs does not do
a great job of handling this case.  The result will be a very
non-optimal file layout and measurably worse performance, especially for
drives with a relatively high average seek time.

-- 
Jon



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