[Coco] Possible CoCo Bulletin Board forum

[Steven Hirsch]

On Thu, 25 Dec 2008, Gene Heskett wrote:

>> It's seriously difficult to kill data on a DLT cartridge.  I've personally
>> seen cases where tapes run over a bulk eraser were still readable!  The
>> drives use read-after-write to ensure integrity and will redo any blocks
>> that fail CRC (up to a limit).  The lack of read-back is a serious issue
>> for the rotary-head transports which are mechanically incapable of it (at
>> least AFAIK).
>
> Bulk erasers don't have the cajones to erase a data or vieo tape unless it
> says Garner on it.

Ah.  Now I know what to look for!  I've been using an older Nortronics 
unit intended for reel-to-reel audio tape.  Whenever I have to wipe a data 
cartridge, I place a U-shaped piece of steel over the top to focus the 
flux lines.  Buzzes like a b*tch, but gets the job done :-).

> Anyway, the virtual tapes, on a 500GB hard drive, are many times more
> dependable, I've not lost a byte since.  And I don't worry about backups, I
> have a user named amanda who runs herself evey morning at a little after 1
> and does all that without any interference from me.

I would be very concerned about putting all my eggs in one basket like 
that.  My working theory on hard drives is that there are two types:

Those that have failed already and those that are about to.

That's why data-retention experts recommend against using RAID for 
archival purposes, BTW.  Just because the chances of losing >1 drive in a 
RAID-5 array are infinitesmal does not mean it cannot happen.

I didn't realize that rotary head devices were capable of supporting 
read-after-write.  Thanks for the update!

Steve


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