Prism Sound Orpheus - Audio Media

For simpler systems, swappable separatedisks actually offer better long-term reliability –unsurprisingly, a disk which isn’t being used at all isless likely to fail than one that’s being used daily.But disks aren’t the only point of failure –motherboards, memory, and power supplies arealso prone to sudden death. An extension of the diskcloning approach is machine cloning. This approachassumes that session data is either stored on externaldisks, or on yet more caddies. With a swappablespare, a dead machine can be swapped out veryquickly, and once external session data is caddiedin or reconnected, the session can be restartedwithin a few minutes. Using a spare machine canraise licensing and copy protection issues, but sincemost software relies on keys and dongles, this isn’tnecessarily the problem it might seem to be.IrreplaceableBecause session data is literally irreplaceable, andalso because it needs the highest disk speedsavailable, it should always be kept on a separatedisk system. The optional RAID card available forApple Mac Pro users makes it possible to addup to four high speed SAS drives inside the MacPro, offering various combinations of speed andreliability. But built-in disks aren’t usually theideal solution at any professional level. There areobvious advantages to keeping session disksphysically separated from working computers.One is portability – for smaller systems, you canpick up your disks and move them to a differentroom. Another is reliability. If a computer failsduring a session, it will always take longer to swapout internal disks than to unplug an externalstorage array.External disks offer a range of connectiontechnologies and storage formats, includingFireWire and USB for local storage, and NAS or SANdrives for networked access. FireWire and USB drivesare an attractive choice for smaller projects, andportable drives are often being shipped betweenfacilities in the same way that tape reels used to be.But units should be selected carefully, and shouldat least offer RAID 10 striping and mirroring.RAID 0 striping is often used for speed, but canbe a data lottery – if one drive dies all of the datais lost. RAID 1 was covered earlier. Budget unitstypically offer either of these options but not both.RAID 10 costs significantly more and uses at leastfour drives instead of two, but is needed to get thebest of both worlds. A combination of FireWire 800connections and RAID 10 will give the best all-roundportable performance.Not To Be Confusing, But...NAS and SAN networked storage shouldn’t beconfused. Both offer remote connection witheither Ethernet cabling or fibre connections toa network, or sometimes to a specialised subnetwork.But otherwise the two technologies arevery different. NAS drives – Network AttachedStorage – have become something of a fad.They’re relatively simple single, double, oroccasionally quad-drive units, sometimes withRAID features, which plug into a network and canbe accessed remotely either as a network drive,as a separate unit on the network, or via a builtinweb or FTP server. But they won’t offer diskspeeds suitable for professional media creation.BACK-UP STRATEGYIn fact they’re better suited for general office work,and also as home music servers. The web serverside can be connected to the Internet for remoteaccess, but these drives don’t offer any gatewayfeatures, so they can only serve media off theirinternal drives. NAS drives are suitable for lowvolumetemporary backups and the sharing ofproject files. But given that disk speeds are rarelymore than 40MB/s, and more typically less thanhalf this, they’re better suited for keeping theoffice accounts than for sharing sample librariesor project video.SAN technology aims much higher. SAN wasdesigned for corporate datacentres, but over the lastfew years has moved into the media mainstream.In the jargon, SAN arrays can be ‘locally attached’,which means they appear as local drives even thoughthey’re connected remotely – which is an essentialfeature for some media applications. SAN disk speedsare very much higher, and can potentially streammultiple channels of uncompressed 4:4:4 HD video.A typical SAN installation includes one or more diskarrays, and a network switch. SAN units run loud andhot, and need a dedicated machine room well awayfrom working suites. Some systems also use extraRAID management hardware that maintains themetadata needed to create a working file system.This can also be done in software – Apple’s XSAN isone example – but the hardware option is typicallyfaster and may be more robust.Avid Tiger ActivityWith products from Apple, Avid, Tiger, and others,there’s plenty of activity in the SAN market, butprices remain high and installation requires>AUDIO MEDIA MAY 2008 53