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Mix Magazine

This installment of The Bitstream column appeared in the August 2001 issue of Mix Magazine.

The Bitstream

This column discusses discusses mid–price tape formats for data recovery…

Roll Tape

How fortunes change. Ampex, the name brings a wave of nostalgia for the days of full track analog and white coats. Nowadays, Ampex intends to sell it’s Data Systems tape storage subsidiary to help fund their strategic redirection into the unproven ASP business space. Best of luck, gents.

While things churn in some circles as we shall shortly see, in others, it’s the tried and true that comfort us huddled masses. I recently attended a series of strategic meetings with a client in Scotland and was struck by the fact that, wherever I went, I heard American music playing. Good stuff, recognized the world over.

Some performances truly are timeless and our digital assets, once born, should be coddled. Which brings us to the topic this month: backing up. “Argh, back ups,” you say, “I’ve got your backup right here!” But have you ever tried to perform a restore of your backup? Who cares if it’s backed up if you can’t restore the doggone thing?

With the slow acceptance of advanced distribution formats like DVD and SACD, file sizes are no longer mere 650 MB trifles. An hour of 96/24 surround will consume 5.433 GB of space. A completed stereo plus surround SACD project requiring a typical amount of editing can easily weigh in at 150 GB. Now, this isn’t a scary amount of data from a management point of view but it does require a bit of forethought and that, dear reader, is my bread and butter.

OK, backups: that usually means tape — data, not audio tape. You can use spare hard disc volumes, either direct or network–attached. With the cost of 30 GB ATA drives down to $99, that’s an option for some. Actually, Gigabit Ethernet–attached NAS makes a great temporary storage buffer for studios needing to move files quickly off working volumes so they can be backed up later. But, for most of us, backups take the form of stationary or rotary head tape formats as either a stand–alone mechanism or as part of a “library,” another name for robotic autoloaders.

Libraries come in many sizes from small, single drive boxes holding 7 cartridges to ‘fridge sized monsters with 20 drives and over 1 TB/hr. sustained rates. Yup, one terabyte per hour. Granted, you may not need such powerful juju but, the ability to fill a cartridge a day for a week’s worth of unattended network backups is a real butt saver from a disaster recovery point of view.

Let’s look at the middle range of tape formats, ignoring the macho ones, like LTO, DTF-2, Mammoth-2 and SDLT, that cost a premium for their superior qualifications and the wimpy flavors, such as the original Exabyte, Travan and DDS-2 formats that have served their purpose and should be put out to pasture. Indeed, the end of the road has come for the DDS family, with no plans to continue past the fourth generation. Looks like what the R–DAT audio format hath spawned will ride quietly into the sunset. What has trotted into town to take up residence are three budget formats whose low end price belies their capabilities.

Billed as bigger, faster and more reliable than a DLT4000, OnStream’s ADR tape format has some interesting features at a price well within any professional’s budget. With a native capacity of 25 MB at 2 MB/second, their LVD SCSI product can be had for around $700. The drive’s several design improvements are intended to reduce tape damage and subsequent loss of data. Trouble is, they're in trouble. OnStream’s business has been rescued by their investors, and only those on high at Philips know what the future holds for the format.

For a few hundred more, the spiffy new features (and then some) of ADR are available in my current favorite, Ecrix’s VXA format. It boasts a native capacity and transfer rate of 33 MB and 6 MB/sec. respectively. A key aspect of the format is the packetization of data written to tape, which allows for data recovery regardless of the order that the data comes in. The VXA spatially shuffles the packets to prevent tape damage or drop outs from resulting in data loss. Moreover, the heads overscan data tracks during read to reduce the need for costly precision head alignment.

Another important feature is VXA’s variable speed transport. This let’s the drive slow down when the host can’t provide sufficient data throughput to satisfy the transport so, less rewinding. Also, since this isn’t a rotary head transport, there’s no need to wrap the tape around a drum. The tape stays in the cartridge, nice and safe.

With extremely robust storage and retrieval specs, you can get SCSI or 1394–attach stand–alone versions for under $1000. In addition, VXA drives are being built into various vendor’s libraries for automatic backup bliss.

I mentioned three mid range formats earlier, the third being DLT1, a low cost version of DLTtape. Space constraints prevent me from discussing it this month but we may look at it in the future.

Given such a groovy welter weight format as VXA, you might think that would be all you’d need. Alas, for DVD and SACD production, a good ol’ DLTtape or AIT-1 drive is still needed to get the image to the replicator. But, for general network backup tasks, these affordable critters can’t be beat.

Sidebar

Remember Kai Winn

If you’ve been trolling the DVD titles lately in search of vintage fun, you may remember Doug Trumbull’s 1983 sci–fi hit, Brainstorm. A vehicle for Louise Fletcher, the evil Kai of Deep Space 9 fame, and the ever buoyant Natalie Wood, the plot hinges on a VR system with direct neural interface. Anyway, the VR box used an optical tape drive to store the mental machinations of the hapless participants. What was once fiction is now reality.

MicroContinuum is the only man left standing [not quite!…see the Tandberg link below - OMas] after a joint venture between Polaroid, Avid, EMC, Lucent, and LOTS Technology gave up on an optical tape–based HD DTV storage product. Polaroid and the National Institute of Standards & Technology have stuck with it, working with MicroContinuum to create a family of write–once and rewritable enabling technologies that promise ultra–capacity, long archival life and a transfer rate of 100 MB/second. That transfer rate translates into 360 TB/hour, for one transport! Just when this stuff will appear in commercial products is unknown but the development team says a 1 terabyte per cartridge product is 12 to 18 months away.

By the way, they’re not the first to attempt this. Both Sony and a group effort by Creo and Euro–giant ICI worked on optical tape products in the early ‘90s with not much to show for it. At the time, the huge capacity didn’t justify the cost. Nowadays, Creo makes computer–based printing equipment and Sony is probably waiting to unleash an optical tape product on the unsuspecting IT world.

Pedant In A Box

Buzz words for this month are…

Terabyte

A terabyte (TB) is 1,000 gigabytes (GB) or 1,000,000 megabytes (MB). In comparison, a double sided, double layer DVD only holds 18 GB. It’s not uncommon for many Fortune 1000 IT departments to have 50 to 500 TB of storage on line. By the way, a byte is 8 bits, with bits being the smallest quanta of binary data.

Disaster Recovery

This umbrella phrase covers a range of methodologies, business practices, technologies and IT strategies aimed at bringing back full functionality after a disaster. Think about where you’d be if a fire, flood or lightning strike took out your entire information infrastructure…sobering, ain’t it?

Bio

OMas, while luxuriating in the blue glow of his new DVD-A player, has been wondering what you folks want to read about in the Bitstream…Check http://seneschal.net/ for e–mail info, related links and informal test results on some ADR and VXA drives (see below).

The Tests

The results of informal tests between the ADR and VXA formats

et’s start by saying that these tests are absolutely non–rigorous! I made no attempt to “level the playing field,” so to speak. All I wanted to see was typical backup performance in my computer with a range of file sizes. Unfortunately, the two evaluation units arrived many months apart, so I couldn’t use the same files on each unit. Also understand that the OnStream product was a SCSI-2 device attached to an Adaptec PCI SCSI HBA, the 3940UW dual channel model. The Ecrix product was a FireWire model, so we’re talking “apples and oranges” here: two very different devices.

Given those conditions, below is the first screen shot, Figure 1. It’s from Dantz Development’s Retrospect application, version 4.3a, and you can see the performance average for that run was 73 MegaBytes per minute. That was an average result with the configuration I had in place. The volume being backed up is a Seagate mechanism in a 3 slot JBOD on the same ultraSCSI chain as the OnStream mechanism.


Figure 1

Now on to Figure 2, a screen shot of the log window showing the VXA drive at work…You can see that, this time, I backed up three logical volumes. Two of them, E Diode and Joshua, are partitions on the ATA internal boot volume. The third, Atlas, is another Seagate SCSI-2 mechanism in the same JBOD. Again, typical results in my system, with a range from 114.2 to 142.9 MB/min. and the average being 131.


Figure 2

What conclusions can be derived from these tests? Only that, on my system, the VXA drive was a good bit faster and beat on the tape a good bit less than the OnStream. The Ecrix is also acoustically quiter, for what that’s worth.

Something to consider with both of these products is that they are both single source formats. There are no other vendors, no second source manufacturers, that make the drives. In general, this is not a good thing as backups tend to sit in storage for a long time and are pressed into service only in dire circumstances. If the mechanism is dead and the manufacturer has gone by the wayside, then you may be in trouble. Also, where there’s no competition, blank media tends to be more expensive. Caveat emptor.