Presently I am using an SDLT220 tape drive with hardward compression turn
on. I have a new LTO2 tape drive and I really do not want to run the
amtapetype program if someone else has already done this. 

Here is my LTO2 drive:

        Product Type: Tape Drive
        Vendor ID: 'HP      '
        Product ID: 'Ultrium 2-SCSI  '
        Revision: 'F63Z'
        Attached Changer: No
        SerialNumber: 'HUL5M02595'
        MinBlock:1
        MaxBlock:16777215
        Ready: yes

I am trying to decide if I want to compress with software or hardware with
the new drive. I see the advantages and disadvantages of each. 


Here is an lto2 tapetype that matches my unit.

-bash-3.00$ /usr/sbin/amtapetype -e 200g -f /dev/nst0 -t Ultrium2
Writing 4096 Mbyte compresseable data: 40 sec
Writing 4096 Mbyte uncompresseable data: 350 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 204800 Mbyte: 35000 sec = 9 h 43 min
wrote 6422528 32Kb blocks in 98 files in 6420 seconds (short write)
wrote 6422528 32Kb blocks in 196 files in 6719 seconds (short write)
define tapetype Ultrium2 {
comment "just produced by tapetype prog (hardware compression on)"
length 200704 mbytes
filemark 0 kbytes
speed 31300 kps
}


In the above case hardware compression was turned on. 

How is length calculated? I would think that the length should be closer to
400G if hardware compression is on.

I am running Solaris 10 on the amanda server. I ran the first part of
tapetype with /dev/rmt/1n(c) where "n" is no rewind and "c" is compression.
I did not specify the "c" or "u" for compression, yet I got "WARNING: Tape
drive has hardware compression enabled".

zorn->[46] > ./amtapetype -o -c -e 200g -f /dev/rmt/1n -t Ultrium2

Writing 2048 Mbyte   compresseable data:  37 sec
Writing 2048 Mbyte uncompresseable data:  76 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 204800 Mbyte: 15200 sec = 4 h 13 min

zorn->[51] > ./amtapetype -o -c -e 200g -f /dev/rmt/1cn -t Ultrium2

Writing 2048 Mbyte   compresseable data:  37 sec
Writing 2048 Mbyte uncompresseable data:  76 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 204800 Mbyte: 15200 sec = 4 h 13 min


Any ideas on how to turn off compression?       

Thanks

Robert

_____________________________________________________________________
Robert P. McGraw, Jr.
Manager, Computer System                 EMAIL: rmcgraw AT purdue DOT edu
Purdue University                         ROOM: MATH-807
Department of Mathematics                PHONE: (765) 494-6055
150 N. University Street                   FAX: (419) 821-0540
West Lafayette, IN 47907-2067            

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