Date: Thu, 01 Feb 2001 09:48:46 -0800 From: Darryl Okahata <darrylo@soco.agilent.com> To: stable@FreeBSD.ORG Subject: Re: ast0: TAPE <OnStream DI-30> Message-ID: <200102011748.JAA24803@mina.soco.agilent.com> In-Reply-To: Your message of "Thu, 01 Feb 2001 18:33:11 %2B0100." <200102011733.SAA66640@freebsd.dk>
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Soren Schmidt <sos@freebsd.dk> wrote:
> Another thing is that for this to work, the drive has to be set into
> a 32.5Kb block mode where the 32K carry userdata, and the 512bytes
> carry block info, like blocknumber etc, since you have to have
> that info when reading, since you must keep track of which blocks
> you have read, since they might be repeated later due to bad spots
> and the above hit'n'write strategy left one double block around...
>
> So, since I have not found a way to deal with this in a satisfactory
> way (malloc'ing 1 Mbyte worth of buffer in the kernel is not fun), the
> support we have can't handle tapes with bad spots on it...
Does the ata device have something analogous to the SCSI
passthrough device (e.g., /dev/pass0)? A long time ago, when I was
looking at implementing a "driver" for the SCSI version of the Onstream
drive, it was much easier to write a userland "driver" that used the
passthrough device. This way, you can malloc() as much space as you
want (the real reason I did it that way, was because it could be much
easier to port to other operating systems).
--
Darryl Okahata
darrylo@soco.agilent.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion, or policy of Agilent Technologies, or
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