ACMES team

Samovar lab

Revisiting storage virtualization for modern devices

Team work: Damien Thenot presented "Revisiting storage virtualization for modern devices" at 4A312 the 20/5/2022 at 10h00.


Since decades, the performance cost of virtualizing a hard drive was acceptable
because a hard drive was orders of magnitudes slower than the virtualization
layer.  However, since a few years, new storage devices with low latency and
high throughput have emerged (e.g. NVMe).  These devices make old storage
virtualization techniques obsolete because the virtualization layer prevents a
virtual machine of fully leveraging modern storage capabilities. Nowadays the
best performance is obtained by using passthrough of a full disk to a virtual
machine.  Unfortunately passthrough prevents the usage of important
functionalities like Virtual Disk Image (VDI) snapshot, virtual machine
migration to another host, storage device sharing with other VMs and everything
where the host might need access to the disk.  Therefore new ways of
virtualizing storage devices need to be developed to enable the best of both
performances that the new technologies bring and functionalities that
virtualization technologies offers.  During this presentation, I will introduce
the current IO software stack in XCP-ng, a Xen based virtualization platform.
And I will discuss the challenges encountered while trying to enhance the
storage software stack of a hypervisor.