freebsd stable - Aug 2016 - Problems while reading from /dev/cd0

Hi,

I'm having some very curios Problems while reading from an BD-R recorded
as a tar directly on the disk without a filesystem.

When i try to read the Disk via 'tar tvvf /dev/cd0'

i get the following output

-rw-r--r--  0 root   wheel 5793264611  1 Jan  2015 file1.db
tar: Error reading '/dev/cd0'
Archive Format: POSIX ustar format,  Compression: none
tar: Error exit delayed from previous errors.

reading the whole file via 'dd if=/dev/cd0 of=backup.tar bs=2048' and
than 'tar tvvf backup.tar' the file is read without a hitch. So the data
on the disk is OK but can't be read directly by tar.

if i try the dd without the bs=2048 i get

dd: /dev/cd0: Invalid argument
0+0 records in
0+0 records out
0 bytes transferred in 0.000115 secs (0 bytes/sec)

So there is a problem reading anything other than 2048 byte blocks from
a Disk.

Reading directly with tar worked in the past. I really don't know how
long it's there but i guess it's since i updated from FreeBSD 9 to
FreeBSD 10.

I running right now FreeBSD 10.3-RELEASE-p4

Here is the output from the kernel boot msg of the BRD Drive.
cd0 at ahcich7 bus 0 scbus7 target 0 lun 0
cd0: <HL-DT-ST BD-RE  BH16NS55 1.00> Removable CD-ROM SCSI device
cd0: Serial Number SIK9JFANE175
cd0: 150.000MB/s transfers (SATA 1.x, UDMA6, ATAPI 12bytes, PIO 8192bytes)
cd0: Attempt to query device size failed: NOT READY, Medium not present
- tray closed

Regards
   Estartu

-- 
----------------------------------------------------------
Gerhard Schmidt                | E-Mail: schmidt at ze.tum.de
Technische Universit?t M?nchen | Jabber: estartu at ze.tum.de
WWW & Online Services          |
Tel: +49 89 289-25270          | PGP-PublicKey
Fax: +49 89 289-25257          | on request

On 23 Aug 2016, at 08:50, Gerhard Schmidt <estartu at ze.tum.de>
wrote:
> 
> I'm having some very curios Problems while reading from an BD-R
recorded
> as a tar directly on the disk without a filesystem.
> 
> When i try to read the Disk via 'tar tvvf /dev/cd0'
> 
> i get the following output
> 
> -rw-r--r--  0 root   wheel 5793264611  1 Jan  2015 file1.db
> tar: Error reading '/dev/cd0'
> Archive Format: POSIX ustar format,  Compression: none
> tar: Error exit delayed from previous errors.
> 
> reading the whole file via 'dd if=/dev/cd0 of=backup.tar bs=2048'
and
> than 'tar tvvf backup.tar' the file is read without a hitch. So the
data
> on the disk is OK but can't be read directly by tar.
> 
> if i try the dd without the bs=2048 i get
> 
> dd: /dev/cd0: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes transferred in 0.000115 secs (0 bytes/sec)
> 
> So there is a problem reading anything other than 2048 byte blocks from
> a Disk.
Have you tried tar's -b option, to set the block size 2048?  Maybe that
will help.

-Dimitry

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