OnStream DI30 and SC30 tape drives

Review date: 9 March 2000.
Last modified 03-Dec-2011.


If you need reliable, regular backups of large amounts of data, you need a tape drive. There's no other technology that fits the bill. CD-R and CD-RW are good for archival storage of medium amounts of data, and the random access you get from a CD is great if you often have to check back on that data. But if you need multi-gigabytes, and only intend to restore your data seldom - generally, the more seldom the better - then tape's what you want.

But if you're a home or small business user, tape drives used to be a big pain.

Tape drives used to come in two flavours. One flavour was achingly slow - such drives often ran from floppy controllers, and not at much better than floppy speed. They didn't have very impressive capacity, either. But they had the advantage that normal computer users could actually afford them.

The other flavour of tape drive was nice and fast, using the SCSI interface, and had ample capacity. And cost an absolute bleeding fortune.

OnStream drives

Things have been changing lately, and some of the front-runners of the new wave of big, fast, reasonably cheap tape drives come from OnStream. OnStream's drives are capacious, fast, easy to use and surprisingly cheap. What's not to love?

The DI30 and SC30 are the internal versions of OnStream's basic "30 gigabyte" drives. They're really only a bit more than 14 gigabytes, of course; see the sidebar to the right. But 14 gigabytes is a lot, and with the compression OnStream's marketing people assume you'll be using you will, indeed, probably fit a lot more onto them. Quite possibly even the 30 gigabytes you see in the ads. Or more.

OnStream also make "50 gigabyte" drives (less than 25Gb, really), but the lower capacity units are likely to be more than adequate for most users.

The SC30 is SCSI, and has a maximum speed rating of 7.2 gigabytes per hour - two megabytes per second. Tape drive speed ratings are more sensibly expressed as a per hour figure, because they're poorly suited to small transfers. The tape spooling and cuing overhead time is much the same whether you're copying 5Mb or 10Gb to a tape; as the size of the transfer drops, the effective transfer rate drops too. Real world performance is unlikely to make it to the maximum speed rating, but it can get pretty close.

8-track lives!

The Advanced Digital Recording (ADR) technology the OnStream tape drives use was developed by Philips; OnStream is actually a Philips offshoot. ADR deals with eight data tracks at once. The late and unlamented eight track cartridge audio tape format, in case you were wondering, could only play or record two of its eight tracks at once.

The multi-track design keeps the tape speed down, which reduces wear and tear; slower tape also means less tape, for smaller cartridges.

The OnStream drives also have a variable speed transport, so they can adjust to write data at the same speed it's being delivered. Tape drives that are too slow just tell the computer to hold its horses while they get the data onto the tape; tape drives that are too fast for the data source, though, can end up taking much longer to do the job, because they have to keep stopping and starting, often spooling back to get to where they were when their write buffer ran dry.

Other cheap-ish tape drives, using the older Travan cartridges for instance, are lucky to manage two gigabytes per hour.

The SC30 has a list price of $US499, which translates to $AU1059 here in Australia, once it's landed and retail-taxed. This is rather steep, for home users, but it's refreshingly - one might go so far as to say amazingly - cheap, for a good-sized, fast SCSI tape drive. Before the OnStreams turned up, much the same thing would have cost you easily twice as much.

The big news, though, is the IDE-interface DI30.

Tape drives still have a stigma among less well-heeled users, which could explain why the DI30 doesn't actually have the word "tape" anywhere on the box. It's a "30Gb Digital Drive", don't you know.

The DI30 will work from the IDE controller on pretty any motherboard made in the last several years, you don't need to buy a separate controller card for it, and it has exactly the same capacity as the SC30. The DI30's speed rating is lower, but still respectable - 3.6 gigabytes per hour, maximum. And it only costs $US299 - the Aussie price is $AU645.

In reality, both drives will end up costing you a bit more, because OnStream rather cheekily don't include a tape with 'em. The 15 gigabyte cartridges only cost $US40 (or $AU95), so it's not that big a deal, but it's still a somewhat underhanded trick.

At least the tapes, like all tapes these days, come formatted. Old, cheap tape drives that came with unformatted tapes could take the better part of a day to prepare a tape for use.

You can get a three-pack of 15Gb tapes for $AU230.

The "50Gb" OnStream drives, by the way, are available only in SCSI, and a plain internal one'll set you back $US699 ($AU1499), plus $US49.95 ($AU115) for your first cartridge.

You'll also, at some point, need to buy a cleaning cartridge; OnStream recommend you use a cleaning cartridge every 90 days if the drive's being used somewhere smoky or dusty. Less frequent cleanings are OK if the environment's not too filthy. The $US39.95 ($AU95) cleaning cartridge is good for 30 uses.


The drives come with software that works with for Windows 95/98 and NT - although the DI30 NT software only works with NT Workstation, presumably because OnStream figure that NT Server users are wealthy enough to pay more for a SCSI drive. Windows 2000 drivers should be coming Real Soon Now.

If you're running Linux, OnStream have drivers and information here.

One thing the OnStream drivers don't have compatibility with, though, is DOS. This means Windows users (for instance) can't zap a hard drive and restore a full backup, without reinstalling Windows first. This slows down the complete restore process a bit.

Setting up

Oddly, both drives use the same small four pin Berg power connector as a standard floppy drive, instead of the bigger Molex connector that's used by pretty much all other drives. There's a pass-through power splitter cable included, that lets you tap a Berg connector off from one of your power supply's Molex outputs, in case you don't have a spare Berg plug available. Apart from the power connector, physically installing these drives is no different from installing any other standard 5.25 inch device; you get the settings right, slide 'em into a bay, screw 'em in, connect the cables and you're done.

That "get the settings right" part isn't too hard, either.

In the olden days, "IDE" was a standard to much the same extent that People's Democratic Republics are really people's democratic republics. Dual IDE devices were supposed to work together on the same cable, and after a while hard drives pretty much did. But if you wanted IDE CD-ROM drives and stranger things, like tape drives, to coexist with hard drives or with each other, you were dreamin'.

All This Has Changed.

The DI30 seems perfectly happy to sit on the same IDE cable as any reasonably recent IDE CD-ROM drive. Either device can be set to Master, as long as the other one's set to Slave; needless to say, the DI30 documentation tells you how to change the setting. There's even a handy-dandy utility on the OnStream software CD that tells you what IDE slots you have free, so you can set the tape drive correctly before you even crack your computer's case.

Putting the DI30 on the same cable as a hard drive will work, too, but it's probably not a great idea to do it. Modern motherboards can handle two IDE devices that use different IDE transfer modes connected to one IDE channel on the motherboard - most motherboards have two IDE channels, each with its own connector. You can put a device whose best mode is Programmed Input/Output (PIO) 3, for instance, on the same cable as a PIO 4 device, and if the drives and the motherboard are all pretty recent then both drives should be able to run as fast as they can; the PIO 4 device won't have to use PIO 3.

But if you put a PIO device on the same cable as an Ultra DMA (UDMA) device - pretty much all current hard drives can use at least UDMA/33, and maybe UDMA/66 - you choke back the hard drive to the old PIO mode. The DI30 is a PIO device, so it should go on the same cable as your CD-ROM, or on a cable by itself, if you want to keep your system performance at its best. UDMA isn't just faster - it also loads up the CPU less. So letting your hard drives use UDMA can do your computer more good than you might think.

The SC30 is a Fast SCSI-2 device, so it'll work from any old low cost SCSI controller. Set the address, set the termination (needless to say, the SC30 has a simple jumper for termination on the back of the drive), plug in and go. If you've got a high cost Wide/Fast/Ultra/Super-Duper (strike out whichever does not apply) SCSI controller, you may need a (cheap) adaptor to plug this little old 8 bit device in.

The Windows software installation from the provided CD is very straightforward, too.

Using them

With a simple single-button motorised cartridge load/eject system, the OnStream drives don't feel cheap. They don't sound cheap, either; in operation, they're about as loud as a quality VCR. This makes them a lot quieter than many other tape drives - heck, than just about any other tape drive.

The impression of quality extends to a simple and sensible dust exclusion measure - if an OnStream drive has no tape in it, and you press the button to open the drive door and extend the plastic "tongue" the tape sits on, the drive won't hang open forever. The green light on the button blinks slowly for a few seconds, then quickly for a few more, then the drive closes itself again while it waits for you to get your act together.

OnStream's 7.2 and 3.6 gigabyte per hour maximum numbers are a bit optimistic, but the IDE drive can genuinely manage more than 2.5 gigabytes per hour, and the SCSI drive can churn through 4.5 gigabytes per hour, or more. This is real transfer rate; with compression, you can back up faster.

Restore speed is a bit longer, but not a lot; to restore a large amount of contiguous data takes maybe 1.2 times the backup time. Restoring a small amount of data can still take several minutes, as the tape spools to the right point, but this is to be expected; tape drives aren't meant for this sort of use.

Neither drive tremendously slows down the system while it does its thing. Old, cheap floppy or parallel drives pretty much paralyse the computer, for hours on end; you can keep on working on a computer that's doing an OnStream backup, with no problems. If you're backing up on an old 200MHz or slower machine then there may be a significant performance impact (especially if you're using compression), but with more recent processors there's plenty of grunt left over.

Somewhat startlingly, you can if you like use the OnStream drives as if they were ordinary random access Windows storage devices. They have their own icon in My Computer, and you can drag and drop files to them, look at their contents in Explorer, and do anything with them you could do with a hard drive.


Windows does not play well with tape drives. Copying data to the drive is OK; one file at a time comes from the nice fast random-access hard drive and is written in sequence to the tape. You may have to wait a little while for the write operation to start, but then it'll cruise along smoothly.

But Windows cannot tell in what physical order files are stored on a tape. So copying the data back again can take a horrendously long time. Windows just requests the files in any old order, and the drive cheerfully obliges. If Windows happens to ask for file 1, then file 2, then file 3, everything's great. But it's more likely to ask for file 106, then file 13, then file 91, then file 7...

Mind you, you can't go past the convenience of just dragging and dropping files to and from the tape. You can go on working on whatever you like while writing or reading, anyway, so as long as you don't mind waiting a while to get back something that you may have copied to the tape much more quickly, you'll be fine.

How long you'll have to wait depends on the size and number of the files you're dealing with. Lots of little files will give you a ludicrous read to write speed ratio - minutes to write, hours and hours to read, for a directory with hundreds of small text files in it. Bigger files, though, can be read in quite a timely fashion. You can fill a tape with MP3 files and play them all back in any sequence pretty smoothly.

15 gigabytes of MP3s is, indubitably, a whole bunch of music. About ten straight days of it, if you're happy with the usual 128 kilobit encoding rate; maybe only a week, if you pick the better sounding 160 kilobit rate.

As well as the drive itself, the OnStream support software creates a separate "catalog" device, set up by default as drive V. It contains separate icons for every tape you've made on that machine. Whether or not the relevant tape is in the drive at the time, you can browse or search the catalog device to see what file's where. To actually access the files, of course, you'll need to put the right tape in and wait.

For more elegant data handling, you can use the bundled backup software, Echo.

Low cost tape drives have, often, come with crummy software or none at all. But Echo is a very good package. It is, genuinely, both easy to use and useful. You can do proper scheduled incremental backups, of local and network drives; it's simplicity itself to set the system up so that all of your important data directories get backed up at two in the morning, every morning. And there are other nifty features, like the ability to right-click a file and select an item on the resultant context menu to restore a previous version, without running the backup software and hunting through a file index.

Echo isn't completely set-and-forget - if you just tell it to back up entire drives then you're probably also going to be backing up silly things like your Web browser cache files. Temp files like these will be changing all the time and therefore get included, pointlessly, in incremental backups. But you really can use Echo properly without reading the manual, if you've any familiarity with backup software at all.

All you have to remember to do is rotate your tapes according to whatever schedule you set. Remember, backing up to one tape that you keep in the backup machine all the time is better than nothing, but it still leaves you royally hosed if the place burns down, or someone steals the computers with the important data on them and the computer with the backup tape in it - particularly easy to do, if these computers are one and the same.

If you use more tapes than you need for the volume of data you have, you can rotate them. Last week's tape can be in a wooden filing cabinet somewhere - things in wooden boxes survive fires - though the boxes don't. The week before that's tape should be a different building. You can have as many more tapes as you want to have backup steps. They all move along one each time you rotate them, with the oldest tape going back into the backup machine.

Echo coexists happily with the plain Windows access to the tape drive, so you can do ad hoc individual drag-and-drop file copies and organised Echo backups to the same tape, as you like.

You don't have to use Echo if you don't want to; the OnStream drives work with other backup software, like for example the popular "serious" backup utilities Seagate Backup Exec and Computer Associates' ARCserveIT (originally from Cheyenne Software). The speed and capacity of the OnStream drives make them perfectly suitable for big business backup applications, despite their trifling (by big business standards...) price. If you're not a big business, though, you're probably find Echo to be perfectly adequate.


Cheap tape drives have, for years, had a hard time keeping up with the capacity of cheap hard drives. It's always been possibly to find an affordable tape drive that takes an age to do anything and doesn't have enough space for a complete backup of your new drive. But the basic OnStream drives are decently priced and sufficiently capacious for a complete backup of even the larger drives on the market today. They're fast, they're easy to use, and they've got good software.


Review OnStream drives kindly provided by Servex.

Buy an OnStream!
Aus PC Market don't stock OnStream drives any more. Various OnStream models still show up on DealTime, though!

Lies, damned lies and tape capacities

Computer storage manufacturers are shameless fibbers, when it comes to the capacity of their products. Disk drive manufacturers - and makers of flash memory cards as used in digital cameras, for that matter - love to specify capacity in powers of ten. For them, a gigabyte is 1,000,000,000 bytes. For everyone else, a gigabyte is two to the power of 30 bytes - 1,073,741,824. There's a seven per cent rip-off right there.

But hard drive marketing people fade into insignificance next to tape drive marketing people. Tape drive capacities are, invariably, specified as no less than twice the actual capacity of the tape. This doubled figure is the capacity you're supposed to get when you use data compression as you do your backups. On the front of the SC30 box, the big yellow "30" is some 70mm high, and the tiny white "Assumes 2:1 compression" is tucked away in the corner, not even 2mm tall.

Now, you probably are going to use compression. With any remotely recent processor, compressed backups take no longer than uncompressed ones - in fact, they're often faster, because the compressed data takes up less space and thus can be written more quickly. But are you going to get 2:1 compression?

If you're backing up really compressible data, sure you are. Text, for instance, routinely compresses down to 40% of its original size. People backing up Postscript files - which are just big fat text files with a lot of redundancy - often get much better figures.

But plain text is, for most users, going to make up a pretty small portion of the data that goes onto a tape. A lot of files are already quite heavily compressed, and the backup software won't be able to make them significantly smaller.

If you're backing up many popular image formats - JFIF (JPG) and GIF, for instance, or compressed TIFF - then you're going to get functionally zero compression. Likewise for many sound and video formats; AVI movie files can be encoded in lots of different ways, with and without compression, but there's a good chance that any recently encoded AVI will use a "codec" that already compresses very well indeed.

If you're archiving plain word processor documents and spreadsheet files, without pictures, you may get compression better than 75%. Microsoft Word document files are notoriously "airy". If those files are full of embedded images, though, you may get much less.

If you're backing up a system drive, and trying to compress program directories, then how far you can squish 'em will depend on the programs. Back up a bunch of Microsoft Office apps and you might get more than 50% compression. Back up a load of other random programs and games and you might get 40%, or 30%, or less, or more. And all compression software isn't equal; the kind of compression your backup software uses can make a few per cent difference as well.

So, for most people, the doubled capacity figure on tape drives might not be far from the truth. Heck, it might underestimate how much you can squish onto a tape. But if you back up a lot of incompressible data, you may get a nasty surprise.

Incidentally, OnStream use both kinds of... misdirection... when they specify the capacity of their tapes. The formatted capacity of a "30Gb" OnStream tape thus isn't even the 15 real gigabytes you'd expect, but in fact a bit more than 15 billion bytes. It works out to about 14.1 real gigabytes.

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