Virtualizing ATA over Ethernet storage systems: Coraid EtherDrive VS21
Székelyi Szabolcs <>
NIIF Intézet
The ATA over Ethernet (AoE) technology provides a simple, cheap and
open solution for storing large quantities of data with small access
latency and for building storage systems fulfilling these
requirements. However, virtualization of storage systems -- making the
physical structure of the storage and the storage needs of the
applications using it independent -- built upon AoE was problematic
since there was almost no chance to aggregate or divide the capacity
provided by single disk drives, moreover, dynamic run-time resizing of
such structures was a hopeless task.
In June 2008 Coraid announced its product VS21 that was meant to
provide a remedy for the problems outlined above, by utilizing the
same logical volume management approach then the one used successfully
on the host side for years now.
In the beginning of the presentation, we provide an overview of the
attributes and features of AoE as a protocol, followed by the brief
history of Coraid products beginning with the EtherBlade and ending
with VS21. We'll discuss the "Physical Volume -- Volume Group -- LUN"
structure used by the VS21, and one of its possible
implementations. We'll also look at how the VS21 transforms the
logical view of the AoE SAN and how it integrates into the existing
infrastructure as well as techniques used by the device to speed up
read and write operations by reducing latency and network
utilization, and also for reducing the load of itself.
In the summary we'll discuss to what degree the device manages to
statisfy the requirements against it, and under what circumstances
is it possible to use it. Missing features that are under
implementation will be identified as well as the ones those are the
result of the design principles og the AoE protocol and the VS21.