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April 30, 2015

The Zen of Atlantis USX on Citrix XenServer: Part III A Simple in Memory Volume

Andrew Wood - Atlantis


What is Atlantis USX software defined storage? How does it work on Citrix XenServer? What does the impact of hyper converged on Citrix XenDesktop/XenApp workloads? If I'm using Citrix XenServer for non-VDI workloads, is software defined storage applicable to me? 

This is Part III in a blog series looking to answer such questions and provide insight into the possibilities of reducing the costs of delivering a virtualised environment while improving the performance: without splitting infinitives.

Atlantis USX can be used to pool SAN, NAS, DAS, and as we'll show here RAM to provide you with optimised storage. With Atlantis USX, you can transition seamlessly from costly shared storage systems to lower cost hyper-converged systems and public cloud storage.

The Atlantis USX and Citrix XenServer blog series covers the following :-  

  • Part I - The Test Environment & Import AMC
  • Part II - Atlantis USX Initial Setup
  • Part III - Creating a Simple In Memory Volume
  • Part IV - Creating a Simple Flash Volume
  • Part V - Creating a Simple Hybrid Volume
  • Part VI Creating a Hyper Converged Volume
  • Part VII -  Creating a Hybrid Volume
  • Part VIII - Management
  • Part IX - Maintenance



Atlantis USX on Citrix XenServer - A Recap 

Atlantis USX (Unified Software-Defined Storage) is a software solution that accelerates performance and consolidates storage, increasing effective storage capacity to support a range of virtualised workloads such as servers hosting business-critical applications, file storage, all components of a Virtual Desktop Infrastructure (VDI) and Server Based Computing (SBC) environment.

The test setup we're using is four (4) Citrix XenServer 6.5 hosts configured in a pool. Each host is has both local disk for capacity and SSD disk for performance/storage. However, there has been an update in configuration due to some issues with XenServer 6.5. Each virtualised host now has 4 sockets, 2 cores per socket and 64GB RAM.

In Part II, we'd discussed the types of virtual volumes available and their uses, and we imported the initial software appliance - the Atlantis USX Management Console - into the pool.

Now let's create some optimised volumes. We'll start with a Simple In-Memory Volume because its equivalent to the Atlantis Diskless ILIO which is very popular with VDI/SBC deployments in stateless/non-persistent deployments. 

What is a USX Simple Volume?

Atlantis USX is versatile in its configuration options. Atlantis USX can provide optimised storage resources on a single host level (USX Simple Volumes). Atlantis USX can also provide optimised storage resources by aggregating resources across hosts (USX Pooled Volumes).

Simple Hybrid, Simple In-Memory, or Simple All Flash volume use only one hypervisor host per volume. For Simple volumes, the storage network requirement is 1 Gbps or faster. While USX has its own High Availability function, USX HA is not support for Simple volumes: that said, if your Simple Flash storage or Simple Hybrid disk storage is on shared storage then you can use the hypervisor's own HA.


What is an Atlantis USX Simple In-Memory Volume?

Atlantis USX Simple In-Memory volumes are optimized to support stateless VDI/SBC instances although they can support other workloads. A Simple In-Memory volume utilises a host's RAM to provide optimised storage for stateless workloads. Fundamentally, server RAM is presented as a NFS/iSCSI storage volume without the need for drivers or modification to your existing virtual machines. RAM storage space is optimised using patented deduplication, compression

RAM? But, how does Atlantis USX Simple In-Memory Storage handle a Host Reboot?

A common concern when using RAM for storage is "what happens when I reboot the host?". The Atlantis SnapClone feature ensures that the data stored in memory can persist between reboots. When you create and deploy a Simple In-Memory volume, a target disk for a SnapClone is automatically configured. The Atlantis SnapClone feature automatically backs up the in-memory storage volume to disk: this disk storage can be local disk, or shared storage. When a host restarts, the startup process of the Atlantis appliances reads the SnapClone backup volume and restores it to the optimised RAM volume. 


Atlantis USX on Citrix XenServer - Deployment of an Simple In-Memory Volume 

The great thing about simple volumes is that you specify the resource and deploy. In the video I do just that. 

  1. Select the host  We have a quick run through of the resources available on the virtualised hosts available. 
  2. Select Hypervisors for Deployment: You then select which XenServer hosts in the pool you'd like to use for creating a USX Simple In-Memory volume. We then select the volume size (96GB in this case) and protocol type (NFS in this case, you could also select iSCSI). You can choose to deploy to all hosts, or just one. We've already defined storage networks in Part II. Note that selecting an 96GB volume will not require 96GB of RAM. The Atlantis HyperDup data services utilise deduplication and compression ensures that the use of host RAM is maximised.  
  3. Automated Deployment The deployment of the software is automatic - the configuration of the volume appliance's network settings, memory, CPU and SnapClone disk is automated. Once deployed, we take a quick look at the resources configured in terms of memory and disk utilisation.
  4. Mount the volume Once deployed, the volume can be mounted as a storage resource to be available for the pool.  

Want to see all that in action? Bear in mind that the video is all done via the medium of mime. 




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