SUMMARY: 20 Gbyte 4mm Tape Auto-Loader

From: Jim O'Reilly (
Date: Fri Oct 21 1994 - 21:19:13 CDT

Original Question:

> I've recently just received a SS2000/Sol.2.3 with a 20 Gbyte 4mm
> tape auto-loader which holds (4) 4mm tapes.
> Question: Is there a software tool that will automatically
> change the tape when it's full to the next one ?
> My preference is using the tar command since I have "large"
> metadevices which are over 20 Gbyte filesystems.

My Thanks to Bruce and Fred and others that responded!

Check with a company called Legato. They have a software package called
Networker and it comes with the tape library driver and can help you manage the backups
and recovers. I highly recommend it. They are the number ONE network enterprise
I highly recommend it. They are the number ONE network enterprise backup/recovery period.
Tech support number is (415) 812-6100 and main number is (415) 812-6000.



Well I've found out both through experimentation and talking to Sun
folks that their DDS drive (4mm) IS ONLY 2GB. The "5GB" they quote in
the literature is based on "estimated compression ratios", but since your
data is already compresses, you don't see much of an effect. The DDS-2
drives that HP makes are 4GB, and I'm going to see about getting that info
for you!

In any case, there is a way to back up files without using 'ufsdump'
(which is not helpful since it dumps filesystems, not files), and to span
many volumes of media. For all backups, you should use the cpio command
with the following syntax:

% find ./dir -print | cpio -ocV -C 49152 > /dev/rmt/Xc

The find command simply echoes the names of files starting in the ./dir
directory (and below) to cpio, which then writes the contents of these
files to tape using blocksize 96 (49152 bytes). Replace the X with the
appropriate tape device number, and use the 'c' even though the
compression won't help much (it'll help a bit).

As the tape is writing, the V flag will make cpio echo a dot ('.') for
each file it writes, just to let you know that something is happening. When
the tape hits the end of media, it will rewind and cpio will say "If you
want to go on, type device/file name when ready.". At this point,
physically eject the tape, put in a blank one (or, if using the
autoloader, "step" to the next tape) and enter the tape device name
(/dev/rmt/Xc) and press enter. The cpio command will continue until all
files are written.

At least this will allow you to back up everything without having to
calculate file sizes and use tar. Make sure you do NOT use rooted file
names in the "find" command, but rather start them from the data source
name directory, like:

% cd /jimbo
% find ./saved -print | cpio -ocV -C 49152 > /dev/rmt/0c

This will save files as:

Do NOT do this:

% find /saved -print | cpio -ocV -C 49152 > /dev/rmt/0c

This will save file names as /saved/UDP/... and will not allow you to
restore file names to different file systems at a later date.
You don't want to have to create all sorts of links when restoring files.

You can also use the cpio command on the 8mm drive in the same manner.


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