Date: Tue, 15 Dec 1998 13:54:48 +1030 From: Greg Lehey <grog@lemis.com> To: mjacob@feral.com Cc: freebsd-current@FreeBSD.ORG Subject: Re: Tape Driver Changes Proposed: Tape Early Warning Behaviour Message-ID: <19981215135448.B15815@freebie.lemis.com> In-Reply-To: <Pine.LNX.4.04.9812141911310.2563-100000@feral-gw>; from Matthew Jacob on Mon, Dec 14, 1998 at 07:15:09PM -0800 References: <19981215132144.H15633@freebie.lemis.com> <Pine.LNX.4.04.9812141911310.2563-100000@feral-gw>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday, 14 December 1998 at 19:15:09 -0800, Matthew Jacob wrote:
>
>>> You *can* enable/disable compression, and we could even make the change
>>> persistent across tape mounts, but the issue here is whether or not you
>>> also want to go and change the N different backup utilities to use the
>>> appropriate ioctl to select compression or not.
>>
>> Precisely. That would also include any tape utilities you port, and
>> any other program you may want to use to access tape. Specifying the
>> function in the device name seems the easiest solution to me.
>>
>
> The only problem with this is that the matrix of device names gets
> extremely unwieldy. It's not just compression, but perhaps density. Take a
> look at the Solaris tape name mess:
>
> /dev/rmt/U{l|m|h|c}[b][n]
>
> U == unit; l = low, m = med, h = high, c = compression; b = BSD semantics;
> n = norewind
>
> and this is where you've (incorrectly, in my opinion) smooshed compression
> in with density selection.
>
> I don't see an easy solution that makes sense (as yet- this requires a lot
> of thinking).
Well, you don't have to go overboard. Combine compression and
density. We have BSD semantics, I suppose, so the only other thing is
no rewind, which we already cater for. So for, say, an Exabyte
8505XL, you'd have:
/dev/rst0l 8202 mode, no compression
/dev/rst0n 8202 mode, compression
/dev/rst0h 8205 mode, no compression
/dev/rst0c 8205 mode, compression
/dev/nrst0l 8202 mode, no compression, no rewind
/dev/nrst0n 8202 mode, compression, no rewind
/dev/nrst0h 8205 mode, no compression, no rewind
/dev/nrst0c 8205 mode, compression, no rewind
Sure, it's more than now, but it shouldn't confuse people too much.
Greg
--
See complete headers for address, home page and phone numbers
finger grog@lemis.com for PGP public key
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19981215135448.B15815>