[Info-vax] Odd tape drive behavior

[David Froble]

Stephen Hoffman wrote:
> On 2013-12-04 20:43:12 +0000, tadamsmar said:
> 
>> I bought a cheap used WangDAT 3900 tape drive of ebay.
> 
> In the best of times, DDS/DAT is write-once read-maybe media format.  
> Even when those do devices work, they still scrape off oxide.  My 
> personal best record with those was one week of daily backups on a 
> cartridge, before the cartridge was trash and the heads needed 
> cleaning.  That was with multiple not-cheap vendors of brand-name 
> cartridges, and regular cleaning passes.  Official spec for most DDS was 
> ~1000 head passes, and whether I hit that on the shoe-shining that VMS 
> normally does with the tape header blocks during MOUNT and BACKUP and 
> related, or if the head pass specs were just optimistic, I never 
> bothered to determine.
> 
> FWIW, The SRM console drivers know how to ask a SCSI device its name, 
> and not much more.   The VMS drivers actually try to use the device.
> 
> Most magnetic tapes are compatible at a basic operational level, so it 
> would appear this drive is either bad, or the command interface is 
> incompatible.
> 
> A cheap DLT/SDLT/Ultrium tape drive would be a more likely to work, and 
> work reliably.  Barring bad cartridges and bad drives, some of which are 
> around.
> 
> Personally, I wouldn't touch DDS with a barge pole.
> 
> 

Even better, get a cheap 4 TB disk drive to hold backup save sets.  Get 
several and mirror them if you're paranoid.

Note: you should ALWAYS be paranoid ....