Date: Thu, 22 Jul 1999 16:09:56 -0700 From: Darryl Okahata <darrylo@sr.hp.com> To: Christopher Masto <chris@netmonger.net> Cc: scsi@FreeBSD.ORG Subject: Re: OnStream status? Message-ID: <199907222309.QAA08849@mina.sr.hp.com> In-Reply-To: Your message of "Thu, 22 Jul 1999 18:42:29 EDT." <19990722184229.A928@netmonger.net>
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Christopher Masto <chris@netmonger.net> wrote:
> Is it a private party? I'd like to get involved, if possible.
> Particularly if the initial work is SCSI, as their IDE drive suffers
> from the same personality quirks.
It's seriously funky.
If anyone's curious, here's a copy of a message that I recently
sent to Matthew (who's doing all of the FreeBSD work).
--
Darryl Okahata
darrylo@sr.hp.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion, or policy of Hewlett-Packard, or of the
little green men that have been following him all day.
===============================================================================
I've been playing with it, and have the following comments:
* The Echo software (the Windows-based software that comes with the
OnStream drive) doesn't write tapes that's even vaguely close to the
ADR development specification. The Echo software appears to be using
it's own format. For example, the AUX data appears to be completely
unused, and the configuration frames are different and are stored at a
slightly different address (for the second, duplicate set of 5
blocks).
* I see OnStream has announced a new "70GB" drive, and this drive will
supposedly be Unix-compatible. However, I don't see how this drive
can read current tapes unless it has a backward-compatibility mode.
* If you know where the bad sectors are (presumably determined when
writing -- I've only gotten as far as reading from the drive),
skipping over the bad sectors seems to result in better performance.
Given this, I'm wondering if it really makes sense to follow the
ADR development specification. In particular, the AUX data is, well,
tedious, and I'm wondering if it's really necessary. One can probably
write a driver for it without following the ADR specs. I believe the
Echo software does this.
As far as compatibility goes, the new OnStream drive can either
read old tapes, or it can't. If it can't, then we don't have to worry
about the AUX data. If it can, then there probably has to be some kind
of compatibility mode; if so, then a driver that one writes, can use the
AUX data as it pleases.
[ Of course, it is possible that the new drive will only read old tapes
that follow the ADR dev specs. I don't think this will happen,
though, as I think that this means that just about every existing tape
will be unreadable in the new drive, because the current software
doesn't follow the ADR specs. ]
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