Tape backup, a resurection of a DAT backup system (originally mentioned in the Damaged USB Drive thread).

[Johny B Good]

In response to a discussion regarding data backup strategies that arose within the "Damaged USB Drive" thread started by Graeme (News), I got to thinking about retreiving the backup data that had remained locked away in a DAT cartridge tape collection for the last 15 or more years.

This came about because of the mention for the need to transfer such backup data (or, more properly, archived data) onto modern media every decade or so in order to keep the backup store viable as the orginal equipment and media inevitably become obsoleted by technological progress.

It occurred to me that I had such an archive stranded on obsolete media (DAT carts) that was in danger of becoming irretrievable since I was relying upon a single DAT drive with which to perform the data restoration.

I mentioned this in my last posting to the thread. For the sake of continuity, I'll simply quote the final 3 paragraphs to get you up to speed.

STARTQUOTE: ==========================================

"If you'd read the whole of my reply, you'll already be aware that I'm looking to resurrect a system to set up the DAT drive in so I can transfer the backups from the 2 and 4GB tape cart collection. As it happens, the SCSI adapter card I have stored with the tape drive is actually a PCI adapter so I don't have to assemble a retro system just for the sake of tape drive itself.

However, it has been such a long time since I last used the tape drive in any system, I'm not sure what backup software was used or even whether I had it running under win2k. I think I was still using win95OSR2 at the time I purchased the tape drive and I'm pretty certain I initially started off with an ISA adapter.

The PCI one may simply be a 'later PCI' version adapter that looked like a suitable substitute for the original ISA adapter, one that may not have actually been used with the tape drive before - I just can't recall. It looks like I'll be gathering the sacrificial livestock and studying the incantations once more. :-("

========================================== ENDQUOTE:

Well, as it turns out, it seems I initially used the DAT tapes using Central Point Software's dos based backup under windows for workgroups, followed by Cheyenne Backup running in windows 95osr2. I don't believe I ran any backup software using the DAT drive after upgrading to win2k SP4 in April 2004.

A quick 'squint' at the tapes shows backup dates from 1997 to 1999. A more thorough look at all of the tapes may show a wider date range when I can haul the tape boxes down from the filing cabinet to allow easier access.

What prompts me to post to a new thread is the fact that I've actually managed to make enough progress sufficient to prove the viability of the tapes and the drive.

I managed to restore a whole 221MB's worth and it only took just over quarter of an hour with the data transfer rate reaching a dizzying

18MB per minute - Yes, that's right a whole 18MB per _minute_ you can see why I ditched the DAT for backup jobs just before the end of the millenium.

It turned out that dealing with the business of setting up the SCSI interface was the least troublesome aspect, no rituals involving sacrificial livestock nor arcane incantations were required. No, the real problem, after discovering that the backup software wouldn't run in win2k, was to engineer a restore from an old Partition Magic disk image of the most recent win95 system disk that had been running on almost identical hardware and then run through the driver update processes due to the slightly altered system resources allocations.

Very early on, the system locked up because I'd forgotten about the need to boot into safe mode so I could delete the now redundent software FSB overclocking utility reference from the startup folder (the A-Open version of the almost identical Jetway BX440 MoBo didn't require such software since it could be overclocked in the cmos configuration. The FSB overclock utility just simply screwed the multiplier settings up, hence the crash).

Eventually I was able to install the driver software for the Intel Pro 10/100 PCI card fitted into this build and got to face the horrors of endless reboots involved in updating the networking protocols in a win95 system. A problem compounded by the fact that the TCP/IP protocol does _NOT_ get added by default, yet the redundent IPX/SPX netware protocol and the NETBUI protocol do get installed by default.

I managed to find the bug free voodoo driver CD straight away and got the graphics driver updated quite swiftly after I had completed my first test of the tape system. It would have been nice to have had that sorted out before running the test but the big priority was to prove the tape system before investing any more time and effort on such niceties as a viewable screen.

It looks like I've got myself a bit of a data retrieval project to keep me occupied for the next few weeks or so. Windows doesn't see the tape drive as something it can handle by itself. I'm relying on the backup software to handle the tape drive operations which leaves me to the tender mercies of the user interface and limitations of the backup software.

I had a google for (free) backup software that was capable of working with DAT storage drives in windows 2000 but the descriptions I looked at for the more promising software failed to mention DAT or tape drives of any sort so I didn't bother trying any of them out.

I might have another look now that I know the hardware is still functioning but that does mean I'll be having to faff about between OSes to try them all out. Any advice in this regard will be more than welcome.

[Chris French]

In message , Johny B Good writes

Good luck :-)

Can't help wondering if there is actually any data that you will actually want on them though.

[Scott M]

I was going say that. To my mind, most data becomes irrelevant before the hardware it's stored on becomes obsolete (and certainly before the hardware has broken down or worn out.)

The small %age of data that does want keeping tends to get shunted between systems during upgrades.

[Johny B Good]

Me too! :-)

However, the only way to know what's worth keeping and what's simply a backup of data that has been migrated dozens of times onto the latest incarnation of the NW 3.11/3.12 fileserver now running as a NAS4Free server box (single 300MB ESDI full height 5 1/4 inch noisemaker to a set of 2, 3 and 2x 4TB silent 1 inch high 3 1/2 inch drives), is to restore the data to seperate folders and take a gander at what was there.

It looks like most of the tapes were 90 metre 2GB carts with a few 60 metre 1.3GB and a quantity of 120 metre 4GB carts. I'm probably looking at a total data set size nearer the 120Gb mark rather than the worst case 320GB ballpark estimate with probably less than 10% of that being of any value over and above what was preserved on the fileserver throughout its many reincarnations and disk capacity upgrades over the past two decades.

I've pulled the 10.2GB HDD with the win2k install out of the drive bay and swapped the 40GB HDD with the win95 install into its place to tidy the box up. I've also pulled out the redundent Teac 32 speed CDROM from between the tape drive in the bay below and the CD re-writer in the bay above to not only give more ventillation space to the tape drive but also to reduce the weight of the box to make it a little more managable.

My next step is to transfer the large plastic media storage drawers from off the top of the filing cabinet so I can more easily sort through the tapes. There are two series of backups, one using Central Point's backup software and an earlier set created using the ancient PC Tools backup software (probably in windows 3.11 or just MSDOS

6.22).

I should be able to run the PC Tools software from DOS7 by restarting windows in dos mode for just this purpose. I don't think there'll be any need to 'dual boot' to cover this contingency.

As far as I can recall, both backup programmes relied on creating catalogue databases stored in the working folder keyed to each tape volume serial number created at format time.

I think it's just a case of getting the backup software to look at the last backup made in each series to read the catalogue stored on each successive tape session to rebuild the database. I think a backed up database was created and added to each tape on every session but I'm not sure of the exact details of this mechanism. I'll have plenty of time to find out though.

[Johny B Good]

Well, as I've already mentioned to Chris, that's exactly the situation I'm anticipating. The thing is, I'm curious to see what 'long lost' software of historical interest may reside within that collection (and any other surprise items long since thought vanished off the face of the planet).

Once I've processed the tapes (and sanitised, if any, dubious content), I'll be able to offer the tapes and the kit to Museums or retro computing enthusiasts, possibly via ebay to get some financial recompense for my not inconsiderable investment in this technological folly. At the very least, it's all going to be disposed of one way or another - it does use up a considerable chunk of storage space compared to a large thumb drive's worth of modern storage.

[Jeremy Nicoll - news posts]

If the DAT drives haven't been used for years I wouldn't be surprised if they've got a bit 'gummed up', for want of better words. Is any part of the mechanism belt driven? Does anything need lubricated (and if so can you actually get suitable lubricant to the right place)? If a tape jams or breaks, is it possible to clear all the bits out of the drive?

If I were you, and if you have any, I'd spool some unused tapes back and forth through the drives before you put a used tape in...

[Mike Tomlinson]

En el artículo , Jeremy Nicoll - news posts escribió:

The most common fault with elderly DAT drives is perishing of the rubber on the rollers. This usually results in any tape inserted being chewed up rendering it useless.

[Johny B Good]

Well, all valid concerns but I just assembled the kit and simply shoved a tape cart into it and did a test recovery without any hitches.

I guess I can count myself lucky in that any rubber used was a vast improvement over the butyl rubber drive belts used in my even more ancient Philips solenoid operated data cassette drives which simply degraded into a gloopy mess about a decade ago.

I've since run another two or three carts through the drive, still without any signs of distress so it looks like I'll be able to complete my project after all.

I'm a little reluctant to carry on without some fettling of the PSU and case ventillation slots to reduce the airflow noise from the PSU fan which I'll try and replace with a less noisy one. It's a little on the loud side as it stands, an issue that's of greater than usual significance in view of the 2 to 3 hour run times for each restore job hence the current hiatus in getting the project properly underway.

If I can examine the tape contents tables, I doubt I'll need to restore more than a small fraction of the tapes anyway but, even so, just scanning the tapes to rebuild the tape contents database is in itself a protracted enough process so I think the time spent on quietening the PC will be a worthwhile investment now that I've proved the the DAT drive is still working ok.

[Mike Tomlinson]

En el artículo , Johny B Good escribió:

It should see it as physical device \\.\tape0

'wmic tapedrive list' at a command prompt will list tape drives recognised by Windows.

Windows Backup will work fine with DAT drives with nothing else required.

[Johny B Good]

Windows 95 osr2 doesn't recognise it as a drive it can use directly for data storage in the same way it can for hard disk drives and floppy disk drives. Afaicr, it shows as a Python 5ACxxxx (different from its orginal name since I flashed the drive's firmware to make it compatible with an audio dat tape player program).

Any data storage functionality is left entirely to suitable third party backup software to handle.

I didn't have win2k compatable backup software to try it with, hence my reverting to win95 to let me recreate the original scenario where I could guarantee access to my old backups.

Unfortunately, I can't recall how it showed itself in win2k's device manager when I did briefly try it out under that OS, swiftly discovering the lack of win2k compatability with the backup software.

The question is though, will it recognise the backup format used by the Cheyenne backup program? I'd have to swap the win2k HDD back in to test that assertion and I've set the PC to one side for the moment to make room for some paying jobs. I'd like to perform some fettling to reduce the PSU fan noise (quieter fan, opened up vent slots, both main case and the PSU case) before I resume the project in earnest.

I'll check out the win2k situation when I next see a slackening off in demand for my services and once more find myself with time on my hands.

[Mike Tomlinson]

En el artículo , Johny B Good escribió:

Almost certainly not. You're on a loser if you expect tapes written by one backup utility to be readable by those written using another. Even different versions of the same backup software can refuse to read tapes written by an earlier version.

You're really best off sticking with the backup provided by Windows - that way, if you wipe and reinstall the OS, you know you'll be able to restore the tapes using the software included with Windows.

Or use something ubiquitous like tar, which will mean you can use just about any OS to read the tapes.