Fair enough, Ron. I recall that we had to replace Exabyte drives more often than 9-track drives. On the other hand, I don't recall ever having an Exabyte tape go bad, or being unable to restore a lost file (or entire drive). Replacing a drive was chump change compared to losing a drive. Plus, the Exabyte tapes were compact, and could easily have a paper label inserted to indicate what was on them when hundreds were stored side-by-side on a shelf. My labels were roundly mocked by Tom Limoncelli in one of his Sysadmin books, but when a user came in wanting a file restored, being able to identify which tape contained the most recent backup was no laughing matter (to the user).

On Mon, Nov 25, 2019 at 4:12 PM <ron@ronnatalie.com> wrote:

Our problem wasn’t so much that the Exabyte tapes would go bad as the drives themselves would keel over on a regular basis. It’s pretty much what drove us away from them. The intelligence community did a lot of studies on archival storage devices. The fundamental truth was to keep refreshed in the online domain rather than spending ages on static media.

From: TUHS <tuhs-bounces@minnie.tuhs.org> On Behalf Of John P. Linderman
Sent: Monday, November 25, 2019 4:08 PM
To: Arthur Krewat <krewat@kilonet.net>
Cc: The Unix Heritage Society <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] Someone wants to use an exabyte

I'm not an expert on mag tapes, but it makes sense to me that 9-track tapes, where the tracks "line up" when the tape is wound onto a reel, suffer more "print-through" than helical scan tapes, where tracks are not aligned with those under them on a reel. I recall a suggestion that 9-track tapes should be mounted and rewound once in a while, to reduce print-through. We used Exabytes for disk backups for years, back when tape capacity exceeded disk capacity. I doubt I'll see that again, but, as noted I'm not an expert on mag tapes.

On Mon, Nov 25, 2019 at 1:35 PM Arthur Krewat <krewat@kilonet.net> wrote:
On 11/25/2019 12:45 PM, Larry McVoy wrote:
> On Mon, Nov 25, 2019 at 12:40:22PM -0500, Arthur Krewat wrote:
>> PS: DAT 4mm tape drives, especially whatever Sun was using, were awful.
> It's no secret that I enjoyed my years at Sun, but I can't defend these
> drives, I had the same experience. When I look back on it, the only
> tapes that I remember being reliable where the 9 track reel to reel
> and the QIC-150. Once it got to GB sized tapes, everything seemed
> like crap.
>

The Exabyte 5GB and up stuff was pretty good. LTOs, after having worked
with them for the past 13 years, I can definitely say, are quit awesome.

DLT tapes and especially robots, well, it took HP about 5 years to get
the firmware right for a certain robot, the model of which, I don't
recall ...

art k.