Blocksize and Compression on 2550 TBU

Ken Rice krice at
Sun Aug 25 17:51:00 CDT 2002

Box is a PE 2550, (Tag B694811)

The TBU is:
Vendor: ARCHIVE   Model: Python 06408-XXX  Rev: 8160
Type:   Sequential-Access                  ANSI SCSI revision: 03

Kernel: 2.4.20-pre4
Star: 1.5a06 (installed only star binary and man page, not mt from the star package)
Data to be backed up: ~60GB, averages 20,000 bytes per file, files are mix of JPG's and
very small HTML's/XML's.
FileSystem: Currently Ext2, but soon to be a reiserfs.

I need to backup about 60GB of data, and am trying to determine the right "options".
(The tapes themselves are 20GB-native/40GB-compressed)

I'm currently doing a backup with:
cd "dirtobebackedup"
star -cv bs=32k -f /dev/nst0 .

1. Is that blocksize proper, or should it not even be specified?
(Tried, no help for this drive)

2. Regarding compression of the data, would this be right?:
star -c . |gzip | sdd ibs=4k obs=32k -fill of=/dev/nst0

I didn't include "ovsize", could that be inserted after "-fill" as: "ovsize=40g" ?

Also, could this enable me to possibly backup all 60GB of data to one tape, although I
know I'm dealing with JPG's?

3. Is hardware compression used by default, without having to be specified?
Or should I export "STAR_COMPRESS_FLAG=-9" first?

Sorry, I know this is perhaps more Star related than Dell, but it COULD be helpful to others using
these TBU's.

Thank you in advance, I hope I've given enough info.

Ken Rice
The Library Corporation

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