I personally am very fond of solutions that handle IO close to the source and therefor give more performance to your virtual machine workload and minimize (or preferably skip) the storage footprint downstream. I previously written a blog post about sollutions you can use at the host. One of these solutions is Atlantis ILIO.
As the company I currently work for (Qwise – http://www.qwise.nl) is also a partner for consulting on and delivering Atlantis ILIO solutions, I thought one plus one is… three. 

If you’re not familiar with Atlantis ILIO, it works with running an Atlantis appliance (VSA) on each of your hypervisor hosts (dedicated for VDI for example) and presenting a NFS or iSCSI data store that all the VMs on that host use. For this data store it uses a configured part of the hosts RAM to handle all reads and writes directly from this hosts RAM (that is when you let the VM deploy here and you have reserved this RAM for this kind of usage). The IO traffic is first analyzed by Atlantis to reduce the amount of IO, then the data is de-duplicated and compressed before being written to server RAM. When needed Atlantis ILIO converts small random IO blocks into larger blocks of sequential IO before sending to storage, increasing storage and desktop performance. This is the IO Blender Effect.
The OS footprint is minimized to a rather small one in RAM, numbers of 90% percent can be reached depending on the type of workload. Any data that will be written to the external storage (outside of RAM) also undergoes write coalescing before it is written. 

Since Atlantis will only store each data block once, regardless of how many VMs on that host use that block, you can run dozens or hundreds of VMs of just a tiny amount of memory.

And what does RAM gives? A warp speed user experience and faster deployment.

Atlantis ILIO can be used for stateless VDI (completely in RAM), persistent VDI (out of server memory or shared storage backed), XenApp and can also be used with virtual server infrastructures.

Atlantis ILIO Architecture

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Like written before Atlantis ILIO is deployed as an appliance on each host or on a host that serves a complete rack. This appliance is an Atlantis ILIO (or ILIO for short) controller or instance. The Atlantis ILIO appliance uses a defined part of the host it’s RAM to present a NFS or iSCSI datastore via the hypervisor. Here you can place the VD’s, XenApp or other needed to accelerate VM’s. ILIO sits in the IO stream of your VM, hypervisor and storage. You need the correct Atlantis product to use the optimized features for the wanted solution workload, currently VDI and XenApp. Keep an eye out for other servers solutions, there bound to come out this half of 2014.
In above model the hypervisor is VMware vSphere with a stateless VDI deployment, but this can be Citrix XenServer or Microsoft Hyper-V as Atlantis supports these also. The Atlantis presented storage can be easily used to accelerate PVS or MCS for using XenDesktop provisioning. Or in combination with some form of local or shared storage for persistent desktops unique user data.

Atlantis ILIO Management Center.

The Atlantis ILIO Management Center will setup, discover and manage one or more Atlantis ILIO instances. The ILIO Center is a virtual appliance that is registered with a VMware vCenter cluster. Once ILIO Center is registered with a vCenter, ILIO Center can discover Atlantis ILIO instances that are in the same vCenter management cluster and selectively install a Management Agent on Atlantis ILIO instances. If additional vCenter clusters with Atlantis ILIO instances exist, then an ILIO Center virtual machine can be created and registered for each cluster.
The ILIO center can be used for provisioning of ILIO instances, monitoring and alerting, maintenance (patching and updates) and for (probably the most importing part) reporting of the status of the ILIO proces and handled IO offload (for example what amount of blocks is de-duped). The ILIO center can also be used to fast clone a VD image. This clones full desktop VM’s in as little as 5 seconds without network or storage traffic.

Hosts and High Availability (mainly for persistent deployments)

Atlantis supports creating a synchronous FT cluster of Atlantis ILIO virtual machines on different hosts to provide resiliency and “zero downtime” during hardware failures. Atlantis supports using HA across multiple hosts or automatically restarting virtual machines on the same host. 

A host that is offering resources to a specific workload, for example the VD’s, this is called a session host. This session host can use local or share storage for it’s unique data storage. With shared storage when a failure happens you can use the hypervisor HA (together with DRS VM rule to keep appliance and VD’s together). When using local storage in vSphere this is not an option as HA requires a form of shared storage. For this you can use ILIO clustering with replication.

With the availability of unique local host data a replication and a standby host come into the picture.

In a Atlantis ILIO persistent VD solution, a replication host is a centrally placed Atlantis ILIO instance that maintains the master copy of each user’s unique data. The desktop reads and writes its IO on the RAM of the session host. The session host (after handling the IO) then replicates any unique compressed data over to the replication host. This replication is called Fast Replication. The replication is handled over the internal out-of-band Atlantis ILIO network. The replication host is shared storage backed where the unique user data is written. There is also a standby host that is a standby for the replication host. This standby host has the same access to shared storage location as the replication host. In case the replication host fails the standby host takes over and has access to the same unique user data on the share storage. Keep in mind that, depending upon your workload, between 5 and 8 session hosts can share a single replication host. 
Disk-backed configurations that leverage external shared storage do not need a Replication Host as ILIO Fast Replication mirrors the desktop data directly from the external storage to this shared storage

For non persistent stateless VD’s the data stays purely in RAM. VMware Horizon View or Citrix XenDesktop will notice that the VD’s are down when the hosts fails, and will make new VD’s available at an other host. Users will temporarily experience a disconnect but their workspaces will reconnect when available again.

Conclusion

With interesting RAM pricing and reducing infrastructure complexity Atlantis ILIO is the perfect solution to use in (re)building VD infrastructure with already in place solutions or solution components. You can provision lighting fast VD’s and engage your workforce to warp speed productivity) with a user cost around 150-200 euro. You can session hunderd of VD’s with just a small amount of configured RAM on one host. Next to this you will have a much smaller unique IO data footprint on your shared storage. No need to go with expensive accelarated storage infrastructure controllers. You can easily go with a cheaper SAN/NAS/JBOD or a No SAN solution.

– Happy Atlantis ILIO’ing!

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