Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!ginosko!uunet!bally!pete
From: pete@bally.Bally.COM (Pete Gregory)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: Determining Density and Cluster Size for Tape Backup
Message-ID: <186@bally.Bally.COM>
Date: 14 Sep 89 01:05:11 GMT
References: <17911@ut-emx.UUCP>
Organization: Bally Systems, Reno, NV
Lines: 58

In article <17911@ut-emx.UUCP>, jjr@ut-emx.UUCP writes:
> I use "cat list | backup -i -f$DEVICE -d$DENSITY -C$CLUSTER"
> to backup files to a streaming tape cartridge.
> What are the appropriate values for $DEVICE, $DENSITY, and $CLUSTER?
> I have been using $DEVICE = /dev/rmt8, $DENSITY = 700 bytes per inch
> (default value), and $CLUSTER = 2000 blocks.
> 
> I use a 3M DC 300 XL/P data cartridge (450 feet, 6400 to 10000 ftpi, 310
> oersted tape).  What does "ftpi" represent, and how does that relate 
> to the number of bytes per inch?  Is 2000 the best cluster size?
> Is /dev/rmt8 the correct device?  Any help would be much appreciated.

Why not use cpio?  We have had great success using HUGE buffers, huge enough
that we REALLY stream the drive (it never stops).

example (to backup /usr/ filesystem):

------- snip ------- snip ------- snip ------- snip ------- snip -------

#!/bin/sh
#
# backusr  -  backup /usr filesystem
#

FILE=/usr/local/bin/Busr
echo "Backup listing will be written to $FILE"
cd /usr
cp /dev/null $FILE
echo "/usr filesystem backup for..." > $FILE
date >> $FILE
nice find . -print | grep -v "./spool/news" | cpio -ovC1000 >/dev/rmt0 2>>$FILE
echo "backup complete at..." >> $FILE
date >> $FILE
echo "backup complete"

------- snip ------- snip ------- snip ------- snip ------- snip -------

...explanations: 

	cd /usr
 	...
	find . -print		- lists all files in /usr filesystem.

	grep -v "./spool/news"	- discard news files (too much to backup  :-[

	cpio -ovC1000		- cpio; 'o' option means backup (vs. restore)
				  'v' options means verbose
				  'C1000' = 1000 BLOCK buffer (512000 bytes)

	>/dev/rmt0		- write to tape drive.  may be different on
				  your system.

	2>>$FILE		- list of files backed up is save to disk.

Pete Gregory   | uucp:   uunet!bally!pete     |      ________   "My boss
Bally Systems  | domain: pete@bally.bally.com | |\ /          \   is
255 Bell St.   | phone:  702-323-6156 x882    | | X   IXOYE    )   a
Reno, NV 89503 | FAX:    702-323-5997         | |/ \ ________ /     carpenter."