SCSI Tape Drives

[Tolis Group BRU|http://www.tolisgroup.com/products/software/macosx/le/devices.php]?

Call the folks?

You might well get help with Mac OS X and Mac OS X Server around here, but I wouldn't expect to get a whole lot of in-depth input (here) around tape support on other Linux and Unix flavors. (There are ways to get at HFS+ volumes on some Linux variants.)

The LTO5 Ultrium series tapes (three terabytes compressed) available from one of the major vendors start at around US$3K, and US$90 per cartridge. You can likely get support on RHEL and some of the vendor-preferred platforms. (Poking around, you might find some other third-party folks that support some of the LTO-series tapes on Mac OS X.)

The cheaper and older and less-capacious tape drives (like the ones that I deal with) don't really hold enough to be bothered with.

I know nothing about tape drives or SCSI, and it strikes me as odd that anybody would want to use either one in this century.

As far as I know, the Mac OS is the only platform with support for journaled HFS, the default filesystem. But you don't need that.

Depending on what kind of data you're backing up, resource forks, or more generally, HFS extended attributes, may not be essential. If they are, encapsulate your backups in an archive such as a sparse disk image, rsync it to the backup server, and transfer it to tape from there.

Tapes are a classic storage mechanism and popular with mid-scale and enterprises, and with some parts of the grey-haired IT set.

They're reliable for ten or twenty years of archival storage. If you purchase the good/expensive drives and the good/expensive media and have the good/expensive archival tools. I've recovered data from some tapes that were written 25 years back. That was good media, decently stored.

These days, tapes and particularly tape loaders and tape libraries probably best suited for tertiary or quaternary storage, and for long-term archival storage. You'll usually see big, cheap, slow disks and virtual tape libraries for secondary archival storage.

Tapes aren't a good first-line storage choice these days. Way too much work and too much cost for what you get, particularly if you have to resort to tape loaders and related hardware. An LTO5 tape storage system can go from US$5K all the way up to, um, seriously expensive.

If you're using cheap tape drives or cheap media or cheap tools, you'll be lucky to recover any files from last week's tape archive.

Now if you have an existing fibre channel with all the (expensive) XP-class disk and (expensive) tape gear hanging off the SAN controllers, then the interest level changes. (But that stuff usually isn't involving host-connected SCSI buses.)

Nice historical collection, but not one I'd prefer to spend a whole lot of money on. (I also deal with old hardware and with enterprise hardware, so I do understand what you're up to here and what you're going through, and I'm very familiar with CD-R/RW, DDS and LTO, and with magtapes as far back as the old GCR-, PE- and NRZI-encoded reel-to-reels.)

Every one of the 4mm and 8mm drives I've tried has been failure-prone, some very nearly write-only media, and with very limited media reuse. (And this was name-brand stuff, with name-brand media.) There may well be good ones out there, but the dozen or so models I've worked with weren't particularly robust, and I nearly had to treat the media as single-use. They're cheap drives that are priced cheaply.

The rated media lifetime on DDS/DAT was on the order of a thousand head passes or so, and the archival procedures I was dealing with could hit that for the tape underneath the tape headers on a dozen reuses or so. Even when it was working, that stuff wore out very quickly.

The DLT and LTO media was rated at some decent chunk of a million head passes, so once you had a batch of media that worked, it could usually be re-used and recycled for a while.

The reason older CD-Rs don't tend to read is usually either low reflectivity, or media degradation. The older CD-R media and older drives were really quite spotty, the drives either weren't sensitive or weren't sensitive to the particular batches of media, or they didn't have the calibrations for the particular media, and the recorded media itself wasn't particularly reflective, and it degrades.

I'd roll those old CD-R disks forward onto newer media, minimally.

And until you're up into the LTO4 or LTO5 range and with the I/O buses to match, tape just isn't a good match for current disk technologies.

Running trailing-edge gear and running a hardware museum (and of which, I fully support) also means you need to differentiate what you're doing to keep your old gear online for historical reasons, and what you're doing to roll forward with and to avoid data loss with the ubiquitous degradation of older media, and what you're doing with your current data.