Avid has produced its shared storage solution for well over a decade which has seen it established as possibly the worlds most popular NLE shared storage solution. With Avid’s latest Unity (version 5) release saw a big change on a number of fronts but 2 of the largest changes were the physical components that made up a unity and more3 importantly the location of the systems metadata.
Pre v 5 Unity
Unity hardware used to be made up of 3 key components
1 - Unity file manager (Intel 2u server - version specific)
This handles requests from clients and maintains and tracks the Unity files systems metadata in RAM. This is the heart of the system and acts like a librarian, directing workstations to the appropriate drives to find media.
2 - Unity Fibre channel switch (Vilex or Qlogic)
This is the interconnect between Server, storage and clients operating at varying speeds depending upon the age of the system (1Gb, 2Gb and 4Gb Fibre Channel)
3 - Unity storage (Avid bandaged Fibre attached JBODs)
This is the physical storage that holds both media AND 3 working copies of the Unity systems metadata (backup up every 20 seconds)
These early Unity systems run with drive block sizes or either 128kB or 256kB, depending upon the version of Unity software they’re running. Ethernet connectivity is only available on early Unity systems via the use of Port Servers (separate Intel servers that ‘bridged’ between Ethernet clients and the Fibre channel storage.)
Version 5 Unity
Version 5 saw a move away from the previous traditional Unity model to something that resembled its baby brother, Unity Lanshare EX. Gone is the separate File Manager server (so losing any fail over possibility) and in is the Avid Media Engine, this chassis now contains 16 media drives as well as the file manager software and is known as an Avid Media Engine. As well as being able to have fibre clients attached it also used the Lanshares model of supporting Ethernet and Fibre clients from the same system without the use of additional servers offering a total of 46 users (26 Fibre and 20 Ether).
Version 5 also saw the block size increase from 256KB to 1MB! While this meant that the system could now handle HD media (especially single large files greater than 2GB i.e. MXF media) for a much reduced metadata count. However this does mean that small files (Project information for example) does make for rather inefficient use of the drive space. For example a 329KB folder or audio render must sit inside a 1MB block meaning that over 600KB of space on this particular block is lost. Which is why shared projects running from v5 Unity may not always be prudent.
A Unity system is still made up 3 components but this has changed too...
1. Unity Media Engine
As in previous releases the Media Engine still fulfils the role of the previous File Manager and handles requests from clients and maintains and tracks the Unity file systems metadata, held in RAM. But just like Lanshare, the system also houses 16 media drives. However, the Media Engine is also the sole location of the Unitys metadata, held on the Engines mirrored D partition.
2. Unity Fibre channel switch (Qlogic only)
This is the interconnect between Server, storage and clients and operates at 4Gbs over Fibre Channel and supports either a single 10port Qlogic switch or up to 2 cascaded 16 port Qlogic switches
3. Unity storage (Avid Fibre attached JBODs)
This is the physical storage that holds ONLY media, Unity metadata is now held entirely by the Media Engine.