jjr@ut-emx.UUCP (09/01/89)
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 $CLUSTER = 2000 blocks. I use a 3M DC 300 XL/P data cartridge (450 feet, 6400 to 10000 ftpi, 310 oersted tape). What does "ftpi" represent, and how does that relate to the number of bytes per inch? Is 2000 the best cluster size? Is /dev/rmt8 the correct device? Any help would be much appreciated. jjr@emx.utexas.edu
pete@bally.Bally.COM (Pete Gregory) (09/14/89)
In article <17911@ut-emx.UUCP>, jjr@ut-emx.UUCP writes: > I use "cat list | backup -i -f$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."
karish@forel.stanford.edu (Chuck Karish) (09/14/89)
In article <186@bally.Bally.COM> pete@bally.Bally.COM (Pete Gregory) wrote: >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. /dev/rmt8 pre-tensions the tape, doesn't it? You probably don't need this if you re-use your tapes every few weeks. I usually use /dev/rmt0. >Why not use cpio? If your system gets trashed, you can re-install it from the standalone diskette if it's a backup archive. The standalone system doesn't include cpio. Read the manual for limitations. Beyond that, the choice of archive format ia a matter of personal preference, usually based on the user interface. IBM people tend to use backup for everything, BSD partisans use tar, USG users favor cpio. >We have had great success using HUGE buffers, huge enough >that we REALLY stream the drive (it never stops). Different utilities have different limitations on the maximum buffer size. Tar re-sets it to 800 blocks when I ask for more. The documentation is unclear, however, as to whether those are 512-byte blocks or 10Kb blocks, the default blocking factor for tar. I'll repeat my call for a generic tape-handling program that understands clusters. The manuals don't give enough information to enable me to write one myself. The worst limitation now is that dd doesn't understand clusters, so I can't use the drive efficiently to do a backup over the network with a command like tar cfb - 1 directories | rsh remotehost dd obs=20 > /dev/rmt0 What's needed is a program that would fit into the pipeline after dd and do the block/cluster management, like the `tcio' program that HP provides for their drives. Chuck Karish karish@mindcraft.com (415) 493-9000 karish@forel.stanford.edu