Customers have begun reporting that HP 3000 backups to DDS DAT tapes are failing to capture all data — jeopardizing the ability to restore files and make truly safe backups. Chris Bartram, creator of the NetMail/3000 application and a consultant at a major US mail-order 3000 customer, reported that he’s found some files cannot be restored on the site’s large backups — even after he’s validated the backups on a second disk drive, a process that savvy users do to ensure backups get done safely. VSTORE, the part of the HP 3000 operating system doing the validation, isn’t reporting problems during backups or validations. But some files nevertheless cannot be restored. The site is using HP’s TurboStore/iX True Online 7x24, backing up on fresh DAT tapes to HP C1537s, the DDS-3 devices so common in the HP 3000 user base.

HP was researching the problem at presstime, but it was uncertain if the results could be conclusive, since HP’s Predictive Support 3000 tool doesn’t gather any data on tape drive failures. Too many errors to record, say HP engineers. Tape drive errors are a fact of life in most backup methods, but the DDS/DAT devices appear far more prone to mistakes than any other medium. That’s what has begun to drive customers with heavy backup loads away from DDS and toward the DLT tape drives, sold by HP and third parties and supported under several backup programs, including Backup + from Orbit Software. The DLT devices and media are more costly than the DDS counterparts, but far more reliable, according to customer reports. The newest DLT7000 units are nearing the magic one-gigabyte-per-minute backup speed in tests at Orbit’s labs, according to engineers there testing the devices with Backup/3000

Until HP testing reveals a flaw in VSTORE, or HP gives VSTORE an option to compare the data on tape with data on disk, Adager’s Alfredo Rego shared his tested procedure to ensure DDS backups are safe: using a separate HP 3000 (with a tape drive other than the one used for the :STORE) to actually restore the files.

Rego reports, “When I am on the road using my Gypsy HP 3000, I do a daily partial backup to a DDS tape, which I mail to Sun Valley (and which [my partner] Rene eventually restores for me on my primary machine as well as on my secondary machine). Not being the trusting type, I massage STORE’s output listing to create an indirect file for LZW (thanks, Randy Medd at Telamon). I produce an LZW file with the affected files and download it from the HP 3000 to my Mac PowerBook. I then upload this LZW file to my secondary HP 3000 in Sun Valley via a phone call and PPP (and I also keep the LZW file, archived by date, on my PowerBook and on the PowerBook’s backups). Once the LZW file reaches Sun Valley, I expand it on my secondary machine, just to make sure that all the files are there. Why don’t I simply expand the LZW file into my primary machine? Because LZW changes the creation and modification dates (which I prefer to keep “true” for historical reasons), so I prefer to RESTORE from one of the TWO DDS tapes which I produce on my last day on the road and which I bring back with me, in addition to the one I mail to Sun Valley and arrives a few days after my return. Should this DDS tape fail to restore, then I would expand the last LZW file into my primary machine. So far, all DDS tapes have worked just fine. It is important to note that, after restoring files (or after expanding LZW files) onto my secondary machine, I schedule a full suite of batch jobs (including compile and link jobs) just to make sure that, besides simply restoring, the files have a fighting chance of being correct.”

Rego’s processes, and the rise of DLT, can ensure that backups remain a worry-free 3000 task, even in the era of 100,000-file backups. It’s a good thing, since DDS seems to be so fragile. 3000 customers say even putting a label on a DDS tape cartridge can put it out of alignment, and cause a restore to fail.