Taking a Closer Look at ARX

Posted 2011-11-04 Print this article Print


The F5 ARX Series of appliances is designed with one key goal in mind: to make enterprise storage easier-easier to manage, easier to provision, easier to secure and, most importantly, easier to use. The ARX Series is available as four different physical rack-mount appliances and the ARX Virtual Edition, a virtual appliance. The five solutions have the same functionality, but differ in performance levels and scale.

The ARX1500 is the entry-level physical appliance in the series and is designed for 3.2G bps of throughput, 3,000 users and 768 million files. Each of those specifications will prove to be very important for those sizing a file virtualization appliance. For example, since a storage virtualization appliance abstracts storage hardware and acts as a proxy for file access, file counts and user counts prove to be of critical importance, as does throughput, so adopters of the technology should choose carefully and consider future network growth and file storage needs.

The big iron in the ARX series comes in the form of the ARX4000, which is rated for 12G bps of throughput, can handle as many as 12,000 users and tops out at 2 billion files. The 4U rack-mounted unit also sports two dual, redundant hot-swappable power supplies, twelve 10/100/1000Mb Ethernet ports and a pair of 10Gb X2 (MM-SC) Ethernet ports.

I was able to perform hands-on testing of an ARX2500 appliance at F5's Lowell, Mass., location. The ARX2500, which began shipping in July, is rated for 8G bps of throughput, 6,000 users and 1.5 billion files. It also supports GbE, although this specific device was attached via 10 GbE to a storage environment that consisted of several flavors of file storage, including NetApp, EMC VNX and Windows 2008 file servers.

Setting up the ARX

Physical setup of the device consisted of little more than mounting it in the rack and connecting the appropriate power and Ethernet cables. The device is designed to support several deployment modes with single or multiple VLAN options, while providing both in-band and out-of-band management capabilities. When inserting the device into the network, it is important to make sure all your cables, subnets and ports are configured properly, ensuring that the device can route all of the storage available on the network.

Initial setup of the device is straightforward. A browser-based GUI is used to launch the setup wizard, which steps an administrator through the basic configuration of the device. One of the first things that needs to be done is licensing the unit. Internet connectivity makes that task a lot easier, so setting up the appropriate networking settings, as well as management IP addresses takes priority. Of course, that would take place after naming the device, configuring the active ports and assigning virtual IP (VIP) addresses. These VIP addresses prove critical for using the device, as we'll see later. There is room for improvement with the setup wizard, which F5 says it has improved in an upcoming release of its software operating system. However, any apt network engineer should be able to work through it trouble free as it stands now.

After initial setup and licensing is completed, provisioning virtual storage becomes the next goal of the setup process. Similar to provisioning storage on a traditional file server, one starts out by defining a "namespace"- essentially, the collection of CIFS shares and NFS exports through which users will access their files. However, the ARX's namespace is slightly different, in that it comprises storage from multiple storage devices, as we'll see in a little bit. But before we can do that, we have to define a few parameters. Namespaces on the ARX can work with CIFS or NFS (and its variants), or multiprotocol, depending on what storage protocols you have already implemented on the network. The same can be said for security; you can choose from Kerberos, NTLM and NTLMv2. Other settings at this juncture include the proxy user account. (With CIFS, that is usually an Active Directory account that has the appropriate rights so that the ARX can access storage.)

After a namespace is created, it is time to populate it. At a high level, a namespace is just a collection of virtual file systems that are grouped into containers called volumes. Think of a volume as comprising all the shares in your home directories, group shares or application workspace, for example. The idea is to construct a virtual file system that federates multiple physical file systems on the various storage devices behind the ARX. The ARX device builds an index of the physical file systems, which in turn is used to create the pointers necessary for the device to act as a proxy to the physical files, while representing those files virtually to the end user.

After you have defined the volumes, the next step is to define what F5 calls, "shares." For those of you already familiar with networked file systems, a share on an ARX is essentially either a CIFS share or an NFS export. As the name implies, shares publish the virtual volume content to the users of storage, allowing them to access their data via the ARX proxy. These shares exist under a virtual service that can export one or more of the virtual volumes to provide seamless access to data that has been virtualized by ARX.

While the process of creating a namespace sounds complicated, the GUI makes it straightforward and provides ample help. It only took me a few minutes to set up a virtual volume, and share it so that it was available to users. That is the magic provided by the ARX's wizard-based setups. Of course, a lot goes on behind the scenes to make virtual volumes work properly, but the ARX appliance handles all of that heavy lifting. IT managers just need to provide the appropriate information to make everything work. Volume creation is probably one area where the most care should be taken. However, if you do make any mistakes, it is comforting to know that the ARX does not change anything on the physical storage device, allowing you recreate virtual volumes, virtual file systems and most anything else with ease.

At this point, it's probably worth a note on how one would actually deploy the ARX appliance. For this test, I created a namespace from scratch in a test environment. It was easy enough; however, most people already have a storage environment with existing users, file data, file shares and storage devices. They will be happy to know that the ARX provides an option that minimizes deployment headaches, which F5 refers to as a "namespace takeover." Here, the ARX appliance actually takes over all of the identifying details of the storage environment it's virtualizing, from storage device IP addresses and fully qualified domain names (FQDN) to the individual share names. The ARX can provide a virtual IP address for each device it takes over to make the environment after virtualization appear identical to the one before.


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