*BSD News Article 82034


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Newsgroups: comp.unix.bsd.freebsd.misc
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From: kxr@netcom.com (Keith Rich)
Subject: Read/Write CDROM strategy
Message-ID: <kxrE02F6o.CGu@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
Date: Wed, 30 Oct 1996 01:37:36 GMT
Lines: 26
Sender: kxr@netcom.netcom.com


I think I could use a Read/Write CDROM to do backup, but I'm not sure
about the strategy to use.  I think the write has to happen all at once,
so I think I want to dd from a disk image to the raw device.  I imagine
having a disk image the same size as the CDROM, and probably on a scratch
disk.  So, it would work like this.

  put the stuff to be backed up on the scratch disk
  dd if=/dev/raw_disk of=/dev/raw_cdrom

The intent here is to end up with a CDROM that can be mounted and looked
at directly rather than having to restore it to disk first.

Now come the hard questions.

  Do I copy the partition stuff as well as the filesystem?
  Can I backup both dos and unix stuff unto the same CDROM?
  Can I end up with a CDROM that I can boot from?
  What about bad blocks?  Can I get bad block info off the CDROM first?
  Are there any limits that will preclude the whole idea?
  Has anybody tried this yet?
  What hardware issues are relevant (e.g.: ide versus scsi)?

Comments?

Keith Rich (kxr@netcom.com)