Re:write data in Tape drive

kmohangoud · 05-19-2008, 03:33 AM

Hai,

How to Read,write data in Tape drive in redhat linux operating system.

lensman3 · 05-19-2008, 07:44 PM

What kind of tape drive? Is it parallel, usb, isa, or a special card. I worked with a HP drive about 5 years ago that would dump about 20 Gig compressed. It was tied to an PATA connector on the motherboard.

The drive access was done through the "/dev/mt" device. The *nix "dump" and "restore" programs did the Level 0 thru whaterev dumplevels. If you want to read and write data look at the "dd" command. We used to use the "dd" command to dump a tape header that wrote the date and filesystems we were dumping. The trouble with tapes is that there were some very obscure and strange commands like "/dev/nmt0" and "/dev/mt0". The only difference was the "n" in front of the "mt0". It meant (I think), when you are done dumping this file to the tape, DON'T rewind the tape because another partition (file) will be following this one. If you didn't put the "n" on the "mt0" then the tape rewound and you would write back over the tape blocks you just wrote out. You wouldn't discover this until you were done!

The other problem with tapes is that there is no "stretch-tape" command. If you want to insert a record into a tape you had to rewrite the entire tape. It was real iffy to rewrite just one record. Sometimes an end-of-file or end-of-tape would be written out and the data following the replace record would just go away. Yes end-of-tape and end-of-file are different tape marks.

Do a "man rmt" to learn everything you ever wanted to about tapes. This could start a flame war, but take the tape drive to a large body of water and throw it in. I'm personally glad this technology is gone., RAID's are a easier solution.

05-19-2008, 03:33 AM	#1 (permalink)
kmohangoud Registered User Join Date: May 2008 Posts: 4 OS: Redhat Linux	Re:write data in Tape drive Hai, How to Read,write data in Tape drive in redhat linux operating system.

05-19-2008, 07:44 PM	#2 (permalink)
lensman3 Registered User Join Date: Oct 2007 Location: Littleton, Colorado USA Posts: 470 OS: xp 64 sp2 Fedora Core 8 (vmware xp core 8 x32) Minix	Re: write data in Tape drive What kind of tape drive? Is it parallel, usb, isa, or a special card. I worked with a HP drive about 5 years ago that would dump about 20 Gig compressed. It was tied to an PATA connector on the motherboard. The drive access was done through the "/dev/mt" device. The *nix "dump" and "restore" programs did the Level 0 thru whaterev dumplevels. If you want to read and write data look at the "dd" command. We used to use the "dd" command to dump a tape header that wrote the date and filesystems we were dumping. The trouble with tapes is that there were some very obscure and strange commands like "/dev/nmt0" and "/dev/mt0". The only difference was the "n" in front of the "mt0". It meant (I think), when you are done dumping this file to the tape, DON'T rewind the tape because another partition (file) will be following this one. If you didn't put the "n" on the "mt0" then the tape rewound and you would write back over the tape blocks you just wrote out. You wouldn't discover this until you were done! The other problem with tapes is that there is no "stretch-tape" command. If you want to insert a record into a tape you had to rewrite the entire tape. It was real iffy to rewrite just one record. Sometimes an end-of-file or end-of-tape would be written out and the data following the replace record would just go away. Yes end-of-tape and end-of-file are different tape marks. Do a "man rmt" to learn everything you ever wanted to about tapes. This could start a flame war, but take the tape drive to a large body of water and throw it in. I'm personally glad this technology is gone., RAID's are a easier solution.