In message <[EMAIL PROTECTED]>, Ulrich Spoerlein writes:
>Hi all,
>
>I just fiddled around with using GBDE for ISO images (it works) and
>stumbled across the need to "guess" the size required for the GBDE
>container.
>
>Looks like the size is not increasing linearly. Here are the numbers of
>512 byte blocks available in md0 and md0.bde
> md0 | md0.bde | diff.
> 2048 1952 96
> 4096 3936 160
> 8192 7936 256
>16384 15872 512
>32768 31744 1024
>65536 63520 2016
>
>So, what's the correct formula?
First off, if you want to use gbde on a CDROM you should use a sectorsize
of 2048 througout (-S 2048 argument to mdconfig).
The amount of metadata in GBDE is pretty straight forward:
1. If do not use off-line keyfiles: deduct one sector.
2. Deduct the key sectors (1 to 4)
3. Find zone size:
nsect = sectorsize / 16
nzone = nsect + 1
4. Find number of zones:
z = remaining_sectors / nzone
5. Find usable size:
size = z * nsect
6. Find overhead/metadata as:
total_sectors - size
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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