Re: Problem mounting encrypted blu-ray disc or image
> 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
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