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Date:      Sat, 1 Aug 1998 14:43:33 -0400
From:      Nathan Dorfman <nathan@fcc.net>
To:        Scott <scott@SchematiX.net>
Cc:        Andrew Bromage <bromage@queens.unimelb.edu.au>, freebsd-stable@FreeBSD.ORG
Subject:   Re: CD writers as a backup medium
Message-ID:  <19980801144333.A12731@fcc.net>
In-Reply-To: <Pine.BSF.4.01.9808011006210.9686-100000@SchematiX.net>; from Scott on Sat, Aug 01, 1998 at 10:10:29AM -0700
References:  <19980801105021.B12513@fcc.net> <Pine.BSF.4.01.9808011006210.9686-100000@SchematiX.net>

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On Sat, Aug 01, 1998 at 10:10:29AM -0700, Scott wrote:
> 
> 
> On Sat, 1 Aug 1998, Nathan Dorfman wrote:
> 
> > On Sat, Aug 01, 1998 at 06:04:01PM +1000, Andrew Bromage wrote:
> > > G'day all.
> > > 
> > > Just wondered if anyone had thoughts on using a CD writer with
> > > FreeBSD-stable as a backup medium.  Does the lack of hard real-timeness
> > > matter? Like, if some other process starts thrashing, will my CD be
> > > ruined?  Is the support for some writers better than others?  Should I
> > > just stick with tape?  
> > 
> > Yes, the lack of hard real-timeness matters. CD writers ideally
> > want a constant stream of data. Depending on the size of the buffer
> > in your drive, you can interrupt the stream for as much as a second
> > or two. However, if some other process starts thrashing and the CDR
> > drive's buffer *is* exhausted, there is nothing more to write and
> > you're SOL, as that CD is now a coaster.
> > 
> > This is why people make filesystems on their hard disk and then burn
> > it to CD. However, if the system is mostly idle, and you have a fast
> > disk, you shouldn't have too many problems backing up to CD. You may
> > want to consider sticking to tape though. Tapes hold what, 4 gigs?
> > CD-ROMS hold 650MB. 
> 
> tapes may be 4GB, but most of them are extremely slow compared to a CD-R.
> Even some of the fastest tape drives aren't as fast as a 4x CD-R (last
> time i checked). Tape drives are also a lot more expensive and the tapes
> are EXTREMELY expensive. CD-R disk can be found for $1 or less if you have
> a rebate. Tapes for my TR1 drive (old; never in use anymore) are $30
> each...and i have 5 tapes for them. So it really comes down to how much
> money you have.

A 90 meter DAT tape can hold up to 4 gigs per tape. You can get them
for about $9 a piece, according to people who buy them. You'll need
6 CDs to back up 4 gigs on CD, that's $6-9. Use the DAT tape twice
and you've already gotten your money's worth. A good CD-R drive is
$400 (SCSI). How much is a SCSI DAT drive, anyone? Plus, I'm not
even mentioning that you can buy 120m tapes for only a few dollars
more.

> > -- 
> >   Nathan Dorfman            |    E-mail:  nathan@fcc.net
> >   Frontline Communications  |  Front desk: 914-623-8553:
> 
>     -scott

-- 
  Nathan Dorfman            |    E-mail:  nathan@fcc.net
  Frontline Communications  |  Front desk: 914-623-8553:

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