frecover part 2 - trouble

[Fred Martin_1]

This is an addendum to my previous frecover thread, closed earlier today.

When I did the fbackup, I used this:

fbackup -g graphfile -v -c fbconf -f $TAPE

I followed it with:

frecover -v -I tapelist -f $TAPE

The tapelist looked great; all files matched my file list of what was in the file systems backed up.

Now I'm doing this:

frecover -x -i /test -v -f $TAPE

I'm trying to restore /test, one of three file systems that were backed up.

But, after the tape blinks away for 3-4 minutes, I get the following:

frecover(2114): read error from input device (I/O error)
frecover(2114): read error from input device (No such device or address)
frecover(2113): unable to resync backup media
frecover(4301): /test not recovered from backup media

...this is very, very bad.

TAPE = /dev/rmt/c4t6d0BEST

That appears correct per ioscan and hasn't change.

Any advice? S.O.S.

Fred

[James R. Ferguson]

Hi Fred:

Try cleaning the tape drive. Do this at least twice. If you have another drive, clean it and try your restore there. If you have a duplicate copy of the backup, try that.

If the 'frecover' fails after cleaning and/or switching tape drives, get a new tape and try 'tar'ing a directory like '/etc' to it. It is possible that the tape drive itself has gone bad.

Regards!

...JRF...

[Steven E. Protter]

Shalom Fred,

I would run some dd read tests on the tape.

Keep trying devices until you get one to work.

It might simply be a bad tape. But the device or address message tells me something else.

Then manually rewind the tape on the command line and you should if there is anything on the tape you should be good to go.


SEP

[Fred Martin_1]

Thanks. I'm remote at the moment but will be going in today or tomorrow and will clean the drive. I'll get back to you.

[Fred Martin_1]

Steven, can you tell me a little more about dd tests? I haven't used dd in about 10 years when I was at another job.

Cleaning the tape drive now. I have an external tape drive which I can hook up if needed. That's been idle about three years but worked when I took it out.

Fred

[Fred Martin_1]

Anyone, this tape drive is alone on a cable, it's the only device on the SCSI card. Can I power off the drive and swap it with another without bringing the server down?

[Fred Martin_1]

Folks,

/test is backed up daily so I tried three tapes, two recent and one a few weeks old. Each failed.

Re-seated cables for the tape drive (model C6375A), nothing there.

I tried swapping in the other tape drive (model C5658A) but couldn't get it to be seen by ioscan. I'm not much of a hardware guy. Seem to recall have to do something special with tape drivers, I don't know. Advice there would be welcome.

Anyway, that means I'm still stuck. It has occurred to me that this drive has been bad for weeks and that all my tapes are useless because of it. Hoping that's not the case.

Interesting that fbackup runs a reasonable amount of time, doesn't bomb. When I pull the tape listing off with frecover -I it gets the listing without complaint. It must be at the head of the tape, it only takes a moment to retrieve it.

On my frecover -x to get /test back, it runs for maybe 6-8 minutes before fail.

/test is a misnomer. The data is development stuff and is important but not modified often. There are 10 or so daily tapes here that have the critical stuff on them.

So, still in a fix.

[Fred Martin_1]

Additional information: for kicks I grabbed a tape that's been sitting around, a temp backup I'd done and labeled November '08. Pulled the tape listing off of it; found a directory on there that had since been deleted.

Restored it, no problem.

So - not a bad drive? But, 15 bad recent backups?

[Bill Hassell]

You are correct. The -V and -I options read the head of thje tape where the header (-V) and a complete index (-I) of all the files reside.

The I/O error indicates that the tape drive could not read the data and then got confused. ioscan is useless as a diagnostic except to indicate that the drive responded to a SCSI ID command. Modern streaming tape drives have extremely high bit densities and can indeed become unreliable after years of usage. You can replace the tape drive but there are many, many models. If this is a DDS drive (DDS is sometimes called a DAT but only plastic case around the tape is similar). DDS drives come in DDS1,2,3,4,5 models and are not backward compatible (ie, a DDS4 tape cannot be read on a DDS3 or earlier).

There also several SCSI interfaces, some are completely incompatible with each other. You can swap tape drives but they should have the same model number. Otherwise, you'll need to post your current model and the others that you have to see what may work as a replacement.

If you have critical data on these backup tapes, there are several data recovery companies that can read most unreadable tapes -- for a price. Reading the data involves very expensive recovery equipment that can be adjusted to compensate for the wear that is causing the I/O errors.

[Dennis Handly]

>This is an addendum to my previous frecover thread, closed earlier today.

Note: You can always reopen your thread and continue there if this is a continuation. Your other thread was:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1352621