>From: Alexandre Oliva <[EMAIL PROTECTED]>
>Date: 18 Nov 2000 05:51:47 -0200
>(i) in case the DLT4000 robot fails, the DLT7000 tape drive will be
>able to read backups done with it, and
>(ii) after the DLT4000 robot is fixed, it will be able to read tapes
>written by the DLT7000 drive.
The autoloader with which I started using amanda was a 7-slot ADIC
device with a DLT 4000 drive (August, 1998).
I had told my manager that sometime around spring of this year, we
should plan on going to a DLT 8000 drive. We did this (though it took
longer than expected); it arrived in mid-October, just before I went on
a 2-week vacation (for the first time in years).
Since we have a dedicated amanda server, it isn't being used when the
backups aren't running (and I'm not tweaking it); I was able to swap the
devices and do some preliminary testing. Basically, the drive worked
just fine without making any changes to the amanda configuration --
though we weren't making optimal use of its capabilities.
Given that I was going to be out of the office for a while, I chose to
leave well enough alone until my return.
After I got back, I found that amanda had run trouble-free; given that,
I started making changes to take advantage of the DLT 8000 -- briefly,
it holds twice as much (40 GB vs. 20 GB native) and writes as much as
four times (6 MB/s vs. 1.5 MB/s) the DLT 4000 drive. (Tape writing
speed is nowhere near the bottleneck now.)
>From this, we may observe that the DLT 8000 drive had no trouble reading
the tapes that had been written with the DLT 4000 drive -- I did not
need to re-label the tapes (via amlabel), for example. And I believe I
did a restore or two, using the DLT 8000 drive, from backups that had
been written with the DLT 4000 drive.
Although I have not tested it, I would not expect that the DLT 4000
could read tapes written by the DLT 8000, though -- unless there's some
way to force the DLT 8000 to *write* in DLT 4000 mode, which I doubt.
I would expect similar considerations to apply to a DLT 7000.
Cheers,
david
--
David Wolfskill [EMAIL PROTECTED] UNIX System Administrator
Desk: 650/577-7158 TIE: 8/499-7158 Cell: 650/759-0823
