Re: Creating dmg on 10.5 and 10.6
Re: Creating dmg on 10.5 and 10.6
- Subject: Re: Creating dmg on 10.5 and 10.6
- From: Axel Luttgens <email@hidden>
- Date: Sat, 5 Jun 2010 14:59:18 +0200
Le 5 juin 2010 à 13:42:46, Rakesh Singhal a écrit :
> [...]
> I am using "ditto -rsrc -V src_file dst_file", does it do any
> compression and copy the data. When I burn it on DVD, it maintains the size.
No, ditto doesn't compress data, unless explicitely told (for example, with the -z option).
But knowing that you've made use of ditto is anyway a useful info (see below).
> I have tried "srcfolder" option and I can create compressed image. But when
> I burn this image on DVD, it expands to equivalent of size of data (around 1
> GB).
>
> Hi Stphane,
>
> Thanks I will try -fsargs with 10.5 and see what happens.
>
> Hi Axel,
>
> If I mount images created on both 10.5 and 10.6, the size data is same but
> image size is different as I mentioned. I will check with "xattr -l <file>"
> but how is it going to help me.
If you really managed on 10.6 to store ±950 Mb of data (as displayed by 10.6) on an uncompressed disk image of 600 Mb, I thought that you perhaps managed to somehow preserve the new file-compression scheme that came with Snow Leopard for its hard disks.
For example, "ls -al /bin/cp" shows a size of 57632 bytes for that executable, while in fact it is compressed and has a logical size of 15473 bytes only on the disk.
In order to achieve this, Snow Leopard transparently stores the compressed data in the file's resource fork and attaches an attribute to the file ("com.apple.decmpfs").
Now, when one copies /bin/cp to a disk image (for example, in the Finder's GUI), it is expected that the copy will be a regular one, not a compressed one, so as to be shareable with previous versions of the OS.
But it looks like that "ditto -rsrc" preserves that "bizarre" format. This seems to be confirmed by a quick trial I've just performed here.
Looks like a ditto bug.
HTH,
Axel
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