Hi, 20.11.2008 02:50, Evaldo Gardenali wrote: > Hi > > I am trying to make Bacula work with my DVD+RW and DVD-RAM media, as raw > devices (similar to tape, but with random r/w support,
Great idea. I'd like to see that as it would eliminate the need for volume part files and dvd-handler and growisofs. That part of Bacula is comparatively unstable, in my opinion. (And I wrote part of the code and helped design the concept...) ... ... > The following scenarios list my test experiences with Bacula 2.2.4 on > NetBSD (I can, again, provide results with a more recent build if necessary) ... > For the following tests, the disk was forced to SPIN DOWN before the > beginning of each run and block sizes were chosen at random, so > real-world speeds should be way greater. > > Small test to demonstrate the RW nature of the device, and the ability > to work with offsets (expected from DVD+RW and DVD-RAM media, unexpected > otherwise) > > goldstein# dd if=/dev/urandom of=1mfile bs=2k count=512 > 512+0 records in > 512+0 records out > goldstein# dd if=./1mfile of=/dev/cd0d bs=2k seek=2 > 512+0 records in > 512+0 records out > 1048576 bytes transferred in 0.774 secs (1354749 bytes/sec) > goldstein# dd of=./1mfile2 if=/dev/cd0d bs=2k skip=2 count=512 > 512+0 records in > 512+0 records out > 1048576 bytes transferred in 0.919 secs (1140996 bytes/sec) > goldstein# cmp ./1mfile ./1mfile2 || echo differ > goldstein# Ok. > Test to demonstrate the random access of the device, as expected from > DVD media. > > goldstein# dd if=/dev/cd0d bs=1m seek=500 count=1 of=/dev/null > 1+0 records in > 1+0 records out > 1048576 bytes transferred in 1.247 secs (840878 bytes/sec) > goldstein# dd if=/dev/cd0d bs=1m seek=700 count=1 of=/dev/null > 1+0 records in > 1+0 records out > 1048576 bytes transferred in 1.518 secs (690761 bytes/sec) What do you get when reading part of a disk that was never written to? And how will you determine EOF and EOM conditions? > Test to demonstrate the random WRITE access of the media (expected on > DVD+RW and DVD-RAM, unexpected otherwise) > goldstein# dd if=/dev/urandom bs=1k count=1 of=/dev/cd0d seek=100000 > 1+0 records in > 1+0 records out > 1024 bytes transferred in 3.046 secs (336 bytes/sec) > goldstein# dd if=/dev/cd0d bs=1k skip=100000 count=1 | hexdump -C > 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > |................| > * > 00000400 > 1+0 records in > 1+0 records out > 1024 bytes transferred in 0.001 secs (1024000 bytes/sec) This one demonstrates that either your /dev/urandom is broken, or it's not that simple writing raw data to and reading it from a DVD. Arno > > Thanks for considering the idea > > Evaldo Gardenali -- Arno Lehmann IT-Service Lehmann Sandstr. 6, 49080 Osnabrück www.its-lehmann.de ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
