Re[03]: Problems with SCSI tape rewind / verify on 2.4.29

[John L. Males]

Hi Marcello,


********** Reply Seperator **********

On (Wed) 2005-03-02 11:34:41 -0300 
Marcelo Tosatti wrote in Message-ID: 20050302143440.GA2543@xxxxxxxxxx

To: Gene Heskett <gene.heskett@xxxxxxxxxxx>
From: Marcelo Tosatti <marcelo.tosatti@xxxxxxxxxxxx>
Subject: Re: Problems with SCSI tape rewind / verify on 2.4.29
Date: Wed, 2 Mar 2005 11:34:41 -0300

> 
> n Wed, Mar 02, 2005 at 12:08:51PM -0500, Gene Heskett wrote:
> > On Wednesday 02 March 2005 07:03, Marcelo Tosatti wrote:
> > >On Wed, Mar 02, 2005 at 11:15:42AM -0000, Mark Yeatman wrote:
> > >> Hi
> > >>
> > >> Never had to log a bug before, hope this is correctly done.
> > >>
> > >> Thanks
> > >>
> > >> Mark
> > >>
> > >> Detail....
> > >>
> > >> [1.] One line summary of the problem:
> > >> SCSI tape drive is refusing to rewind after backup to allow
> > >verify> and causing illegal seek error

In my experiences with this problem that I am sure is exactly the same
issue, the tape in fact does rewind after creating the tar to then
perfore the --verify option.  The illegal see error seems to arise
after the rewind or more correctly bsf commands may be being used (but
not confirmed this yet, another test I need to do in few days).  For
sure the tape is positionted back.  I know as I have also done this
test with larger directories and know and have heard the tape take
long time to naturally get back to the start of tar file to be able to
perform the --verify option.  That said I am using a DLT drive. 
Perhpas with different drivers or tape drivers this issue may have
variations on theme and behaviour with net result the same error
message and/or root cause.

> > >>
> > >> [2.] Full description of the problem/report:
> > >> On backup the tape drive is reporting the following error and
> > >> failing it's backups.
> > >>
> > >> tar: /dev/st0: Warning: Cannot seek: Illegal seek
> > >>
> > >> I have traced this back to failing at an upgrade of the kernel
> > >to> 2.4.29 on Feb 8th. The backups have not worked since.
> > >Replacement> Drives have been tried and cables to no avail. I
> > >noticed in the> the changelog that a patch by Solar Designer to
> > >the Scsi tape> return code had been made.

Last kernel to work correctly in 2.4 branch was 2.4.26.  Kernel
versions 2.4.27, 2.4.28 and 2.4.29 all fail based on my experience
with DLT SCSI based tape.

> > >
> > >v2.6 also contains the same problem BTW.
> > >
> > >Try this:
> > >
> > >--- a/drivers/scsi/st.c.orig 2005-03-02 09:02:13.637158144 -0300
> > >+++ b/drivers/scsi/st.c 2005-03-02 09:02:20.208159200 -0300
> > >@@ -3778,7 +3778,6 @@
> > >  read:  st_read,
> > >  write:  st_write,
> > >  ioctl:  st_ioctl,
> > >- llseek:  no_llseek,
> > >  open:  st_open,
> > >  flush:  st_flush,
> > >  release: st_release,
> > >-
> > 
> > Interesting Marcelo.  How long has this been true in 2.6?

In the 2.6 tree the tar --verify works with 2.6.7, but fails with
2.6.9. I am unable to test 2.6.8, but based on research of the code
changes of 2.6.8 compared to the changes made in 2.4.27 re llseek I
would expect 2.6.8 to fail as well with my DLT SCSI tape. 

> 
> Actually I just checked and it seems v2.6 is not using "no_llseek".
> 
> However John L. Males reports the same problem with v2.6 - John,
> care to retest with v2.6.10 ?

My ability to test a 2.6.x kernel is limited to what 2.6.x kernel I
can find on a livecd.  The 2.6.7 and 2.6.9 kernel tests I conducted
were using Knoppix 3.6 and 3.7.  I do not have means at this time, nor
time, to build up a dedicated drive to test 2.6.x kernels.  If someone
knows of or can build a 2.6.10 kernel on a live CD I will be happy to
do the test.  That said, I looked at the patch for 2.6.10 and seems
alot of changes were made to st.c in 2.6.10.  I did not see, but could
of missed in looking, any lseek related change in 2.6.10.  Given how
it seems the test I ran with the change in st.c Marcell suggested what
is the expected thought on this issue with 2.6.10?  I am just asking
from curiousity.  Again, if someone can tell me of a live cd or can
easly make a live cd with the 2.6.10 kernel I can test this issue wiht
2.6.10.  Perhaps there is someone else with a DLT/SCSI tape driver
that could test this tar --verify issue on 2.6.10?

> 
> > I thought I had an amanda problem, and eventually went to virtual 
> > tapes on disk, largely because of this.  However, I have to say it
> > is working better than tapes ever did here.  Unforch, that 200GB
> > disk is certainly a single point of failure I don't relish
> > thinking about...
> 
> :)


Regards,

John L. Males
Willowdale, Ontario
Canada
02 March 2005 (15:00 -) 15:46


==================================================================


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Boomer 1985 (Born), Adopted 04 September 1991
04 September 1991 - 08 February 2000 18:50

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"Hello Miss Chicago 'White Sox', how are you 'Chico'?"
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