we currently use a HP DLT Vs80i tape drive with NTBACKUP (via batch script and AT command scheduler) to backup up approximatley 31.5Gb of data via a 10BaseT network with all the servers on a 100BaseT backbone. There are 9 DLT tapes used for daily backups. The details of the setup are below
Windows NT4server SP6a.
Adaptec 29160 Ultra 3 SCSI card (recommended by HP)
HP Vs80i DLT tape drive
HP branded DLT tapes
The backups script is of the format below:
ntbackup backup G: H: /d"Accounts" /hc:on /t normal /l "c:\Accounts.txt" /e
ntbackup backup "F:\sales /a /d"Sales" /hc:on /t normal /l "c:\Shares.txt" /e
ntbackup backup I: /a /d"Marketing" /hc:on /t normal /l "c:\Marketing.txt" /e
The mapped drives point at network shares. This was working o.k for about six months when it started showing "Bad Blocks on Tape\0" errors on the Windows NT event log (Event ID 7) and the backup failed along with the tape cleaning (amber) light flashing intermittently. I cleaned the tape drive and tried running the backup again only to find it produced the same error. It seems to fail about the same time every night (approx 4 hrs into backup). I have run all the HP tape tools and diagnostics and they all test the tape and the drive o.k with the correct expected data transfer rates. I don't beleive that the drive or the tapes are at fault.
I then noticed the following in an HP driver README.TXT
The HP SureStore DLT 70 and 80 tape devices are designed for use in the high performance server environment. In order to realise the full performance of this tape drive it is necessary to use a third party backup application
and not the ntbackup ‘applet’ supplied with the Windows NT operating system. The DLT 70 and 80 tape drives have a higher performance than the ntbackup utility, which can only supply data at 2 MB/s (without data compression). This is insufficient to maintain the HP SureStore DLT 70 or 80 drive in ‘streaming’ mode and will result in frequent stopping and repositioning of the tape.
I phoned HP and they suggested I try a third party backup application to see if that produces errors. I tried to do this and because the tape was written with windows NTBACKUP the application I was using could not erase it, so I could not do that. I erased the tape with NTBACKUP and then tried to run the backup script again but it failed part way with "No tape in drive 1" and "Inconsistencies have been found on Drive. Do not append to this tape". This happens on different tapes and they all pass the HP media validation tests. They are alos only about 3 months old.
I then used an old copy of Ultrabac that we used and it seems to be backing up (a lot faster) and correctly.
I know this is a lot of detail but I would like to get to the bottom of this error rather than just using a third party app. I have seen various solutions like disabling wide negotiation on the SCSI bus but nothing specific. Does this mean that I cannot use NTBACKUP with this drive and definetly need a third party app as NTBACKUP cannot provide the tape drive with the data fast enough?
Any assistance or pointers would be much appreciated.