Copy data from tape

newFreeBSD · 04-16-2012, 08:06 PM

Hi,

I having problem copy data from tape. The is Archive Python tape drive. This is what id do:

Step 1

Code:

tar -b 512 -tvf /dev/st0

Got some error:

Code:

tar: /dev/st0: Cannot read: Input/output error
tar: At beginning of the tape, quitting now
tar: Error is not recoverable: exitting now

Step 2

Code:

mt -f /dev/st0 status

Show block size 512 bytes.

dd copy not working. No data copy. Please assist me.

Thanks.

jlinkels · 04-16-2012, 09:15 PM

Since you are able to issue the mt command, I assume you have the correct permissions. But just to be sure, try your first command as root.

Overall, this looks an awful lot like a failing tape drive or failing tape.

jlinkels

newFreeBSD · 04-16-2012, 09:38 PM

Yes, i did in root permissions. Are you confident tape problem? I think so but i need solid proof to report my manager.

jlinkels · 04-17-2012, 05:07 AM

Tape or tape drive. Try another tape, perform a write/read sequence. You could also attempt to run a cleansing tape. ButI can tell you for sure this is not a driver/software problem. The bits on the tape are not appearing correctly on the output of the drive. That is a mechanical or physical failure.

jlinkels

newFreeBSD · 04-17-2012, 08:30 PM

This is 4mm tape drive. Last time i read 3590 and 3592, with same pc no problem at all. Some of my friend said this 4mm sometimes complicated. Let me give some example:

1. Tape A cannot be read by tape drive A but it can be read by tape drive B. Either way around.

rknichols · 04-17-2012, 10:38 PM

Are you sure the tape was written with a 512-byte block size? Check /var/log/messages for an "Incorrect block size" message. You can find the actual block size by putting the drive in variable block size mode and then trying to read a huge block:

Code:

mt -f /dev/st0 setblk 0
dd if=/dev/st0 of=/dev/null bs=64k count=1

The messages from dd will tell you how much was in that one block. If that is something other than tar's default block size (10240), you'll have to tell tar the correct size ("-b" option) as well as having the drive in the correct mode.

gdejonge · 04-19-2012, 06:40 AM

Sounds awfully like a miss-alligned head. How long ago was the problem tape written?

1. As jlinkels suggested try a new tape and do a write and read the data back.

2. You are sure the data was written with tar and not cpio or dump?

3. Did you try a cleaning tape?

newFreeBSD · 04-19-2012, 07:02 AM

This tape is year 1990. You must be surprised. This data very important.

---------- Post added 04-19-12 at 08:03 PM ----------

Nothing error on /var/log/message

gdejonge · 04-22-2012, 11:03 PM

Not really surprised. The problem is in the fact that your heads got miss-aligned. This is a commen problem with drives that use a helical scan system. The only option you got is to have a professional company to re-align the heads so they can read the old tapes.