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Mini-Howto for verifying a selfmade CD
1) verifying the data layer
To verify if all data on the disk can be read,
use SCSI verify. This can be done with the
sformat utility.
use: sformat -verify [target] [lun] [scsibus]
If the CD-R device is connected to target 2 on SCSI bus 0
sformat -verify 2 0
sformat can be found on ftp://ftp.berlios.de/pub/sformat
NOTE: Not all CD-ROm drives support verifying
NOTE: All TAO tracks end in 2 unreadable run-out sectors
2) verifying the filesystem layer
A quick check is to mount the CD and to use star to read
all files on the filesystem.
mount -r /dev/cdrom /cdrom (modify for your OS)
cd /cdrom
star -cPM . >/dev/null
If no errors can be found, all files are readable.
star can be found on ftp://ftp.berlios.de/pub/star
You also may want to compare the filesystem on the CD
with the original data. This can be done with star too.
(cd /master_for_cd; star -cPM .)|(cd /cdrom; star -diff -v)
2a) verifying the iso image before creating the CD
You may check the filesystem image by mounting it with my
"fbk" on Solaris or the loopback driver on Linux.
On Linux type:
mount isoimage.raw -r -t iso9660 -o loop /mnt
On SunOS type:
mount -r -F fbk -o type=hsfs /dev/fbk0:isoimage.raw /mnt
For Solaris 8 and later you may also use the Sun lofi driver (see README.sun-lofi)
The check the filesystem with:
(cd /master_for_cd; star -cPM .)|(cd /mnt; star -diff -v)
When doing this you have to know about the bugs in Linux/Solaris
Mkisofs before 1.10 and Linux have a bug with timezones.
If you are using mkisofs-1.10 and newer on Linux, you need to disable
comparing times:
(cd /master_for_cd; star -cPM .)|(cd /cdrom; star -diff -v diffopts=!times)
The same is needed if you are using mkisofs pre-1.10 on Solaris
Solaris has a bug with hardlinks. It generates different inode numbers
for the hardlinks to a file. This makes it impossible for star to
check hard links. Use
(cd /master_for_cd; star -cPM .)|(cd /cdrom; star -diff -v diffopts=!hardlink)
in this case.
NOTE: Some operating systems have a read ahead bug that causes I/O errors for
the last file(s) on a CD. This seems at least to be true for all Linux versions
and for Solaris 7 FCS. For Solaris 7 there is a patch (107465-02) that you should
install. This I/O error problem does not occur with DAO disks and with TAO disks
that have been written with cdrecord -pad.
Joerg Schilling
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