Hi, Am Dienstag, 24. Juli 2012, 17:53:02 schrieb Eric Bollengier: > >> What you describe is exactly what the code is supposed to do, but it > >> works well only if you restore to a filesystem that supports "sparse > >> blocks", and a raw device doesn't support it. > > > > ACK. I haven't found any hints in that sense in the documentation. > > > > As said, not only the restore device needs to support sparse blocks, but > > also the backup device ... > > No, the backup device doesn't need to support the sparse block > interface
OK, let me put it in other words: if the backup device was a raw device, the restore to a file (non-raw-device) will not result in an exact copy of the original data. > >> If you restore the device image to the filesystem then you copy it with > >> dd to your device, it will work. > > > > As long as said device has been nulled before. > > Not in this case (not easy to implement that saids), when restoring to > the filesystem, empty blocks will contains zeros, then when you copy the > result file to the raw device, dd will copy zero as well. Incorrect. When I back up a device that ends in zeros (a "hole"), and restore the data to a file, the trailing zeros are not written, as the final seek will not extend the file size appropriately. Due to that, dd'ing these data back to the/a device will only result in correct data if that device was nulled before. > I think that if Bacula was able to write zeros on sparse blocks when > restoring to a raw device, it would be nice, however, it might be a bit > tricky to implement, because you can write to the empty area only after > you received a new sparse stream and you detected a sparse area. See one of the next mails for a patch that implements that. Thx again Bastian -- Collax GmbH . Basler Str. 115a . 79115 Freiburg . Germany p: +49 (0) 89-990 157-28 www.collax.com Geschäftsführer: Bernd Bönte, Boris Nalbach AG München HRB 173695. Ust.-IdNr: DE270819312 ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Bacula-devel mailing list Bacula-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-devel
