> No > cryptsetup luksClose /dev/mapper/BDbackup > between remove and burn ?
To be honest, I cannot say for sure, so maybe yes. But: what would be the implication? The fs inside is already unmounted, is cryptsetup luksClose modifying anything within the image? > Andy Polyakov decided to format BD-R by default. Possibly because he used > an operating system (IIRC, Solaris) which did not expect that BD-R can be > used for multi-session. So its mount program followed the volume descriptors > starting at block 16 rather than at 16 blocks after the start of the > youngest session. > Whatever, growisofs by default wants to update the volume descriptors at > block 16 of the BD-R and for this uses BD-R Pseudo-Overwrite formatting. > This special feature uses the Defect Management to replace old written > blocks by newly written blocks. > > Formatted BD-R cause the drive to perform Defect Management when writing. > This means half write speed at best, heavy clonking with smaller write > quality problems, and often miserable failure on media which work well > unformatted. Ah, I remember, some years ago before I started using BD I had a look at there specification. > That's why i riddle why your burns do not fail in the end. > What do you get from a run of > > dvd+rw-mediainfo /dev/dvd INQUIRY: [PIONEER ][BD-RW BDR-209D][1.30] GET [CURRENT] CONFIGURATION: Mounted Media: 41h, BD-R SRM+POW Media ID: CMCMAG/BA5 Current Write Speed: 12.0x4495=53940KB/s Write Speed #0: 12.0x4495=53940KB/s Write Speed #1: 10.0x4495=44950KB/s Write Speed #2: 8.0x4495=35960KB/s Write Speed #3: 6.0x4495=26970KB/s Write Speed #4: 4.0x4495=17980KB/s Write Speed #5: 2.0x4495=8990KB/s Speed Descriptor#0: 00/12088319 R@12.0x4495=53940KB/s W@12.0x4495=53940KB/ s Speed Descriptor#1: 00/12088319 R@10.0x4495=44950KB/s W@10.0x4495=44950KB/ s Speed Descriptor#2: 00/12088319 R@8.0x4495=35960KB/s W@8.0x4495=35960KB/s Speed Descriptor#3: 00/12088319 R@6.0x4495=26970KB/s W@6.0x4495=26970KB/s Speed Descriptor#4: 00/12088319 R@4.0x4495=17980KB/s W@4.0x4495=17980KB/s Speed Descriptor#5: 00/12088319 R@2.0x4495=8990KB/s W@2.0x4495=8990KB/s POW RESOURCES INFORMATION: Remaining Replacements:16843296 Remaining Map Entries: 0 Remaining Updates: 0 READ DISC INFORMATION: Disc status: appendable Number of Sessions: 1 State of Last Session: incomplete "Next" Track: 1 Number of Tracks: 2 READ TRACK INFORMATION[#1]: Track State: partial incremental Track Start Address: 0*2KB Free Blocks: 0*2KB Track Size: 12032000*2KB READ TRACK INFORMATION[#2]: Track State: invisible incremental Track Start Address: 12032000*2KB Next Writable Address: 12032000*2KB Free Blocks: 56320*2KB Track Size: 56320*2KB FABRICATED TOC: Track#1 : 14@0 Track#AA : 14@12088320 Multi-session Info: #1@0 READ CAPACITY: 12088320*2048=24756879360 While for a readable disc I get: INQUIRY: [PIONEER ][BD-RW BDR-209D][1.30] GET [CURRENT] CONFIGURATION: Mounted Media: 41h, BD-R SRM+POW Media ID: CMCMAG/BA5 Current Write Speed: 12.0x4495=53940KB/s Write Speed #0: 12.0x4495=53940KB/s Write Speed #1: 10.0x4495=44950KB/s Write Speed #2: 8.0x4495=35960KB/s Write Speed #3: 6.0x4495=26970KB/s Write Speed #4: 4.0x4495=17980KB/s Write Speed #5: 2.0x4495=8990KB/s Speed Descriptor#0: 00/12088319 R@12.0x4495=53940KB/s W@12.0x4495=53940KB/ s Speed Descriptor#1: 00/12088319 R@10.0x4495=44950KB/s W@10.0x4495=44950KB/ s Speed Descriptor#2: 00/12088319 R@8.0x4495=35960KB/s W@8.0x4495=35960KB/s Speed Descriptor#3: 00/12088319 R@6.0x4495=26970KB/s W@6.0x4495=26970KB/s Speed Descriptor#4: 00/12088319 R@4.0x4495=17980KB/s W@4.0x4495=17980KB/s Speed Descriptor#5: 00/12088319 R@2.0x4495=8990KB/s W@2.0x4495=8990KB/s POW RESOURCES INFORMATION: Remaining Replacements:16843296 Remaining Map Entries: 0 Remaining Updates: 0 READ DISC INFORMATION: Disc status: appendable Number of Sessions: 1 State of Last Session: incomplete "Next" Track: 1 Number of Tracks: 2 READ TRACK INFORMATION[#1]: Track State: partial incremental Track Start Address: 0*2KB Free Blocks: 0*2KB Track Size: 12032000*2KB READ TRACK INFORMATION[#2]: Track State: invisible incremental Track Start Address: 12032000*2KB Next Writable Address: 12032000*2KB Free Blocks: 56320*2KB Track Size: 56320*2KB FABRICATED TOC: Track#1 : 14@0 Track#AA : 14@12088320 Multi-session Info: #1@0 READ CAPACITY: 12088320*2048=24756879360 > Your way of creating a big image has the disadvantage of needing > extra disk space. Cool would be to write directly to the BD-R. But it > is a block device only for reading, not when it gets written.) Absolutely ;-) > I have a backup use case where i define an encryption filter and apply > it to data file content. The filter makes use of an external encryption > program which can operate on data streams. (In this case it is self-made > from some published encryption algorithm. But any stream capable encryption > program which can read the key from a file should do.) > It is for multi-session. So the /dev/mapper approach will meet more > problems. I doubt that dm-crypt handles growing devices. Since I didn't find anything like that I went for the image file solution, which - while not being "pretty" - should at least work and I'm not disk space limited (at least as far as the size of a BD is concerned). Best, Bernd
