On Mon, 6 Nov 2000, mike ledoux wrote:
> I've taken the liberty of crossposting this to the main GNHLUG
> discussion list, as there may be others who are interested in this.
Most likely. Backups are usually the most neglected thing in a system.
:-)
>> I have a SCSI 20/40 DDS4 Seagate tape backup configured on a Linux
>> platform. I'm trying to research how to use it, but all I find is ftape
>> which apparently doesn't support SCSI tape drives.
It might be worth stressing something here:
"ftape" stands for "floppy tape", and it is the kernel-level device driver
for tape drives which connect to the FDC (Floppy Drive Controller) port. It
is not backup software. Rather, it lets backup software use the tape drive
without having to need to know the details of how to talk to the tape drive.
Other, similar kernel drivers include "st", for SCSI tape drives, and "ht",
for IDE tape drives. All of these kernel drivers present a uniform interface
to userland backup software. Thus, backup software only needs to know how to
use the standard tape interface, not the details of each individual hardware
interface.
But wait -- there's more! :-)
You will find the "built in" backup software isn't just one program. In
typical Unix fashion, several discrete components are used to build a working
backup solution. One of these components is the kernel driver mentioned
above.
The next is the "mt" (magnetic tape) command, which mike ledoux already
explained how to use. "mt" takes care of generic tape operations, like fast
forwarding, rewinding, and ejecting.
Once you've got your tape ready to go, a device-independent program like
"tar" takes over. "tar" doesn't care what it writes to (or reads from) -- it
just opens up the file or device you pass it, and starts writing (or reading).
The same goes for "dump", "cpio", "afio", and most other backup software. It
is up to the operator (or a more sophisticated front-end program) to use
commands like "mt" to position the tape in the right spot for reading or
writing.
> If it is a SCSI tape drive, you need to make sure that your kernel has
> support for SCSI tape devices.
You can check to see if that support is available by looking at the
/proc/devices file. You should see a line like
9 st
if the SCSI tape driver is available. If you have a modular kernel, the SCSI
tape driver module may be available but not loaded. The command
modprobe st
, when run as the "root" user, will load the SCSI tape module if that is the
case. Note that it is remotely possible that this could hang your system if
you have flakey or misconfigured hardware, so use a bit of caution when doing
this. (Rule of thumb: *Always* use a bit of caution when "trying things" as
root. :)
> Others might include 'cpio' in that list, but I've never cared for it
> much.
There is a backwards-compatible replacement for "cpio" available called
"afio". The main reason I mention it is that it includes a feature for
file-by-file compression, compared to the data stream compression "tar" uses.
If the tape develops a bad block, gzip can lose sync and die. With afio, you
just lose the current file; with tar, you can lose the whole session. It
really sucks to lose a 4 GB tape just because of one 512 byte bad block.
> If you're looking for something a little more fancy, I've heard good
> things about Amanda (http://www.amanda.org/), but I've never used it
> myself.
While Amanda is definitely a good system, it might be a bit of overkill for
the average home user.
Programs geared more towards single-user/home systems include "taper" (a
long time standby on Linux systems) and "KBackup" (a text-based program which
pre-dates the KDE Project and has nothing to do with it). URLs are
<http://www.e-survey.net.au/taper/> and
<http://sourceforge.net/projects/kbackup>, respectively. I think there are
graphical front ends for GNOME and KDE as well, though I haven't looked for
any myself (I'm a command line kind of guy).
There are also commercial programs which support Linux. BRU, NovaNET,
ARCServe, and Arkeia all come to mind. YMMV.
Hope this helps,
--
Ben Scott <[EMAIL PROTECTED]>
Net Technologies, Inc. <http://www.ntisys.com>
Voice: (800)905-3049 x18 Fax: (978)499-7839
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