topic Re: Dat drive problem, wont read in Operating System - HP-UX

Dat drive problem, wont read

David Preston_4 — Mon, 19 Nov 2001 20:02:37 GMT

Hi I have a k200 wit a dds2 dat drive. I can write to the tape, but I can not read without a directory checksum error. I have replaced the drive, the Core I/O controler, and even the scsi cable. and it will not read (tar -t) I have also used fbackup / frestore with no success. Does anyone have any suggestions???

Dave

Re: Dat drive problem, wont read

Uday_S_Ankolekar — Mon, 19 Nov 2001 20:07:59 GMT

Hi,

Did you rewind the tape before read..?
If not try with mt command
mt -f /dev/rmt/omn rew

than do a tar -tv

Goodluck,
-USA...

Re: Dat drive problem, wont read

Marco Paganini — Mon, 19 Nov 2001 20:14:16 GMT

Hello

Use the /dev/rmt/0m device. It should rewind the tape automatically for you. Also, try to *clean* your DAT drive with a cleaning cartidge! The drive heads need to be cleaned or else you'll have all kinds of problems.

Regards,
Paga

Re: Dat drive problem, wont read

Darrell Allen — Mon, 19 Nov 2001 20:14:51 GMT

Hi David,

Has this just started happening? Perhaps you can try specifying the tape drive:
tar cvf /dev/rmt/0m /tmp
tar tvf /dev/rmt/0m

Are you sure the drive's device path hasn't changed perhaps due to hardware added?

Darrell

Re: Dat drive problem, wont read

A. Clay Stephenson — Mon, 19 Nov 2001 20:17:41 GMT

Hi David:

Although you did not mention I assume that you have tried different tape. What I want to do is get tar, fbackup, etc. out of the picture and talk to the drive directly. Try this:

dd if=/stand/vmunix of=/dev/rmt/0m (or whatever). This may take some time as you are writing in 512-byte blocks.

Next dd if=/dev/rmt/0m of=/tmp/xx

Now let's compare the two files.

cksum /stand/vmunix
cksum /tmp/xx

If they differ, I want you to use od to find where things go wrong. It will proably be on a block boundary.

The only other thing that I can think of is bad termination. I can't remember on these boxes if the terminator is built on to the end of the internal cable or whether you have to enable terminal on the last device on the bus. Also, is terminator power enabled on at least one device on the bus? A bad terminator would do exactly the things that you describe. The other thing that would cause this is termination being applied to anywhere except the ends of the cable.

Happy hunting, Clay

Re: Dat drive problem, wont read

David Preston_4 — Mon, 19 Nov 2001 20:34:49 GMT

OK, I have to admit that I did not give you all the facts, so here it is from the top,
I picked up the machine used, and it had previously had this issue, I have never gotten a tape to properlyu read or recover from this device. 1st I replaced the scsi cable (including terminator) no change. 2nd I changed out the drive with a new one, both drives were able to write a tape I could read on another system. 3rd I changed out the Core IO, all parts have come from a reliable vendor so I would think that the hardware is fine, the only pieces of hardware not checked are the interface panel on the back of the disk cabinet, but that is basically a pass through, and the backplane, which frankly if thats what is wrong I am out of luck. the only consistant thing is that the error always says "directory checksum error" but it happens in a different place each time. every copy I have done has been in a directory of multipl files, I have not tried a single file.
Other than that I don't know what to tell you.
Is it still worth doing that block write? what can I deduce from the stoppiong place of the recovery?

Dave

Re: Dat drive problem, wont read

A. Clay Stephenson — Mon, 19 Nov 2001 20:44:47 GMT

Okay Dave:

This is now sounding much more like a software problem than a hardware problem. Have you checked for all the latest SCSI/tape patches?
I really suspect a problem with the stape driver.

Re: Dat drive problem, wont read

Sanjay_6 — Mon, 19 Nov 2001 20:47:30 GMT

Hi David,

Can you post your ioscan output. Also Do you have proper driver configured in the kernel. What is the syntax you are using to copy data and read data from the tape.

Regds

Re: Dat drive problem, wont read

David Preston_4 — Mon, 19 Nov 2001 21:07:45 GMT

Hi, thanks for all the feed back:
here is the ioscan:
ioscan
H/W Path Class Description
===============================================
bc
8 bc I/O Adapter
10 bc I/O Adapter
10/0 ext_bus GSC built-in Fast/Wide SCSI Interface
10/0.0 target
10/0.0.0 disk HP C2490WD
10/0.3 target
10/0.3.0 disk HP C2490WD
10/0.4 target
10/0.4.0 disk HP C2490WD
10/0.5 target
10/0.5.0 disk HP C2490WD
10/0.6 target
10/0.6.0 disk HP C2490WD
10/0.7 target
10/0.7.0 ctl Initiator
10/4 bc Bus Converter
10/4/0 tty MUX
10/4/8 tty HP J2094A - 16 Modem MUX
10/12 ba Core I/O Adapter
10/12/0 ext_bus Built-in Parallel Interface
10/12/5 ext_bus Built-in SCSI
10/12/5.0 target
10/12/5.0.0 tape HP C1533A
10/12/5.2 target
10/12/5.2.0 disk HP DVD-ROM 6x/32x
10/12/5.7 target
10/12/5.7.0 ctl Initiator
10/12/6 lan Built-in LAN
10/12/7 ps2 Built-in Keyboard/Mouse
32 processor Processor
34 processor Processor
49 memory Memory
#
also attaching text file

how do I find out about the driver software?

Dave

Re: Dat drive problem, wont read

A. Clay Stephenson — Mon, 19 Nov 2001 21:17:01 GMT

Probably the best answer at this point is to install the latest General Release patchset.

Re: Dat drive problem, wont read

Frank Slootweg — Tue, 20 Nov 2001 13:51:11 GMT

Have you checked the syslog.log and dmesg(1M) output for errors? Note that both are buffered, so you may see the errors only some time after they occured.

Also please post a failing tar(1) example (assuming that the "directory checksum error" is from tar). Please post the full commands, options, parameters used and *all* messages, not just the message(s).

Re: Dat drive problem, wont read

David Preston_4 — Tue, 20 Nov 2001 14:21:38 GMT

Re: Dat drive problem, wont read

Sanjay_6 — Tue, 20 Nov 2001 14:36:22 GMT

Hi David,

Try this commands,

CD /etc
tar cvfb /dev/rmt/0m 20 /etc
tar tvfb /dev/rmt/0m 20

cd /tmp
mkdir test_dir
cd test_dir
tar xvfb /dev/rmt/0m 20

Hope this helps.

Regds

Re: Dat drive problem, wont read

Darrell Allen — Tue, 20 Nov 2001 15:05:12 GMT

Hi David,

Please post the output to these:

ioscan -fnC tape (use the n option so you get the device path)

ls -l on every device path for the tape drive from your ioscan

Hopefully ioscan shows /dev/rmt/0m since that's the default for tar. And hopefully ls -l /dev/rmt/0m looks okay.

Thanks,
Darrell

Re: Dat drive problem, wont read

Volker Borowski — Tue, 20 Nov 2001 15:19:25 GMT

Another approach:

Insert a DDS3 tape into the drive. If it is not automatically ejected, you may have a jumper problem (MRS ist set to inactive).
In this case, it may be possible, that the drive does not switch to the appropriate density when writing.

Are you trying DDS1 or DDS2 media ?

Do not know if this helps
Volker

Re: Dat drive problem, wont read

Volker Borowski — Tue, 20 Nov 2001 15:20:59 GMT

Darell has a point,

in addition check environment variable $TAPE, in case the default is overridden !

Volker

Re: Dat drive problem, wont read

David Preston_4 — Tue, 20 Nov 2001 15:31:28 GMT

Re: Dat drive problem, wont read

Carlos Fernandez Riera — Tue, 20 Nov 2001 15:45:35 GMT

Hi David:

For i have read you tape drive is broken. It can write but have lots os problem while reading.

First check this thread:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x298bee3e323bd5118fef0090279cd0f9,00.html

There there is a source of a full DDS diagnostic source. I had to wite it because lots of problems with four DDS2 i an K server. Due to intensive use of this drivers i had to change a drive each two months.

Compile and run it. Run tar again and run it again. Search for differences. It must losts of raw retrys and Error correction algorithm.

2- Change method of read. Now use
dd if=/dev/rmt/0m of=/dev/null bs=10k

Its very posible that dd return I/O error.

Change driver and use new tapes, because due to errors tape sould be degradated.

Re: Dat drive problem, wont read

Frank Slootweg — Wed, 21 Nov 2001 07:38:07 GMT

I wrote, but got no answer to:

> Have you checked the syslog.log and dmesg
> (1M) output for errors? Note that both are
> buffered, so you may see the errors only
> some time after they occured.

I agree with Carlos that your DDS drive is probably defective. Contrary to what their name implies, DDS drives are effectively analog devices which work like video-recorders (i.e. using the heliscan technique). While *normally* very reliable, they can develop problems, especially alignment problems, resulting in intermittent behaviour like you are experiencing. So my advice is to have the drive checked/repaired/replaced.

Re: Dat drive problem, wont read

Paula J Frazer-Campbell — Wed, 21 Nov 2001 09:15:32 GMT

David

Errors occuring at different places ???
Could be software, but unlikly.

Go for the weakest link -

Change the Dat drive , yes I know that you have done it once but how certain are you that it is 100% OK.

Paula