a question about tar

[gary_35]

i input a tape into tape driver ,it is a 24G tape ,i wanna use it tar a file which is 14G,when i use tar cmd ,it is show that i should use 2 tape to tar this file ,i am confused by it,i think the tape is big enough for the file,whats wrong ?

[Tom Ward_1 · Accepted solution]

You didn't state what type of tape drive you're using. If your tape drive is a DDS3 tape drive. It would hold 12G native and 24G compressed. Depending in the type of data you which to tar to tape, it may not compress.

Regards,
Tom

[Jeff Schussele]

Hi gary,

Yep, Tom's correct.
2 to 1 is an avg - ONLY.
If it's more binary-like than text-like, it's highly likely that dog won't hunt.
Only thing you can do is verify that IF the drive has a compression controlling DIP Sw, it's not in the detrimental position. The drive will compress at it's best ability otherwise.

Later,
Jeff

[monasingh_1]

What you can try is /dev/rmt/c#t#d#BEST
device file for highest comp and density. do
man 7 mt
mor more details...

tape drives normally are set to do compression, so the BEST option should work for you...

hope this helps...

[Bill Hassell]

AS mentioned, tape drives are always rated at twice their 'normal' capacity. So 14Gb might fit but there are no guarentees without knowing how compressible the data might be.

But most important, /usr/bin/tar on HP-UX cannot backup a 14Gb file. It can backup hundreds of 2Gb files but the industry standard headers prevent storing a file size larger than 2Gb. If your file is truly 14Gb then tar won't be appropriate. You need to pick a program that is large-file compatible for both the backup and restore machines. For HP-UX, you can use fbackup/frestore. but for other systems, you'll need to work out compatibility issues.

[Norman_21]

Hello,

Add to your notes that tar GNU will support large file systems.
download it from here.
http://gatekeep.cs.utah.edu/hppd/hpux/Gnu/tar-1.13.25/

Good luck.

[Yogeeraj_1]

hello,

you may also consider compressing (gzip) the file before tar'ring it to the tape drive.

hope this helps!

Best Regards
Yogeeraj

[Stanimir]

Hi!
I thing you could use another command
to archive this file /tar, even GNU-tar is
not supported large files/. Try fbackup.
Regards