Atlantis ILIO Diskless VDI – An Alternative Approach


Atlantis ILIO Overview

While at Synergy in Anaheim in May, one of the booths that garnered quite a bit of attention from attendees was that of Atlantis Computing.  They were demonstrating ILIO, their VDI solution that ran a desktop at a rather remarkable speed.  ILIO comes in a variety of editions suitable for XenApp, persistent VDI, diskless VDI and what they call FlexCloud.

In a nutshell, ILIO utilizes RAM as primary storage for the applications.  In the context of VDI, this can mean a huge performance gain for the write-cache necessary to operate desktops.  The “magic” VDI number for IOPS has been (sometimes jokingly) stated as 15-20 IOPS.  Realistically, if you deliver only 15-20 IOPS to a Windows 7 user, they’ll probably riot.  The ILIO solution skirts that issue by using RAM as the primary storage.  But why would you use Atlantis when we’ve seen this type of solution before?  The “secret sauce” lies in the fact that ILIO de-duplicates and compresses memory on the fly which dramatically increases scalability and makes the cost model for cache-in-RAM applications quite feasible.

After our successful VDI pilot, our VDI environment expansion “target” was to expand VDI by as much as we could given the budget and other environment design goals we laid out.  Our core infrastructure consisted of 3 HP DL380 G7’s (144GB),  1 HP DL380 G8 (192 GB) backed by an EMC VNX5500 block device serving ~4000 IOPS from spinning drives fronted by FAST Cache.  All told, this pilot environment was stable, dependable and worked quite well.  The trouble was expanding it was going to be somewhat expensive.

Atlantis has an advantage with ILIO because the price of RAM has come down in recent years.  It is quite possible to pack servers with 256-384GB of RAM for easily less than $10,000.  Other than the additional RAM requirements, ILIO’s competitive price comes from being entirely software.

 

ILIO Diskless VDI for Hyper-V

Upon beginning our initial evaluation, I was met with the unfortunate reality that once again Hyper-V is “stuck in the IT-past” to paraphrase the now-defunct “VM-Limited” Tad.  Atlantis ILIO Diskless VDI for Hyper-V does not have feature parity with the current version for ESX.  The ESX current version is 4.0, while Hyper-V is stuck at 3.2.  Atlantis was quick to point out that they are working tirelessly on Server 2012 support as well as making sure there is feature parity.  In addition, there is no ILIO Center for Hyper-V, meaning all ILIO instances need to be monitored individually.  This is key, because if the ILIO volume fills to capcity it is “game over”, so to speak.

With that aside, the installation and configuration of ILIO was extremely simple.  ILIO presents its RAM storage as a 2-TB iSCSI LUN via an internal Hyper-V network to the Hyper-V host.  you then provision your VM’s to that storage and away you go.  If the ILIO VM powers off for any reason, all data on the volume is gone and you must reprovision the VM’s again after restoring ILIO.

Performance

IOMeter and HD Tune were used to measure the I/O performance and compare to our disk-based storage.  In a head-to-head test, our storage array actually won out in some write tests (likely due to the large controller cache then FAST Cache) but was consistently smoked in reads.

Random Access Read - VNX5500 Random Access Read - ILIO  ILIO File benchmark - Random dataFile Benchmark - VNX5500 - Random Data

However, it is important to note that this took place when the storage system was basically idle.  At scale, our expansion will see a maximum of 770 desktops in concurrent usage.  Our storage expansion plans could offer us an additional 16,000 I/O, to bring the total to 21,000.  ILIO, on the other hand, showed 25,000-28,000 IOPS maximum – a point that is key considering you will receive that I/O ceiling per host.  With 10 servers, that means we’ll be pitting 250,000 IOPS potential vs 21,000.

Recommendation

At this point the finalized pricing has yet to come in for our additional expansion components, however, we’ll be recommending obtaining Atlantis ILIO.  The peace-of-mind knowing that you’ll basically “always” have enough IOPS to deliver a killer VDI experience is a huge motivator, even given the drawbacks of their Hyper-V edition.  Given the aggressive positioning Microsoft has been doing with Hyper-V, I am hopeful vendors will start to see it as a serious competitor and grant an equal development priority to ensure their products truly can remain hypervisor agnostic.

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