Hello, Thanks for replying... was hoping that someone would respond!
I was referring to the fields: UInt16 drEmbedSigWord ;//embedded volume signature - formerly drVCSize and HFSExtentDescriptor drEmbedSigWord ;//embedded volume location and size - formerly drVBMCSize and drCtlCSize
I think what you mentioned about Wrappers is relevant to what I wanted to know though I don't see the purpose of having a HFS+ partition embedded in a HFS volume (?). Why would anyone want an embedded partition when all data could be stored in the original HFS partition? I've just set these fields to 0 right now and I fail to see a situation where I (a third-party HFS-volume developer) would ever need these. Any tips?
Regards, Nandini Hengen
----- Original Message ----- From: "Simon Bazley" sibaz@sibaz.com To: "Entwicklung" entwicklung@whengenibk.de Cc: hfs-user@lists.mars.org Sent: Friday, February 22, 2002 2:51 PM Subject: Re: [hfs-user] Embedded volume..
I'm not sure exactly what you're referring to, but heres a few pointers.
The volume is the thing that you mount on your computer which provides files. It represents the single mount point which appears as a disk on your computer. The HFS Wrapper is a HFS partition consisting of a massive consecutive bad block file, which happens to be a HFS+ partition thats embedded in the HFS volume. The important difference between HFS+ and HFS is that wheras in HFS certain files (Device Drivers, Boot System Files, Allocation Bitmap) exist at various physical disk locations (sector 0, sector, sector 4 etc) and the MDB only gives the location to the Catalog and Extent files. Also there are 2 different address spaces, physical (in sectors), and logical (in blocks, starting at 0, after the end of the volume bitmap, at the location described in the MDB as the start of free space). HFS+ has very little (if any) system files at fixed locations, and everything is referred to in the volume descriptor (replaces the MDB), in the way the Catalog and Extent files was before.
Hope that explains everything, if not give me the names of the variable in the HFS and HFS+ volume descriptors and I'll explain what they mean.
Simon
Entwicklung wrote:
Hi, what exactly does the term embedded volume mean? I've noticed that the HFS MDB has some fields related to this but the HFS+ volume header doesn't seem to. I'm not really using these fields but I'd like to know what they're used for in any case. So if anyone could enlighten me I'd appreciate it. Regards,Nandini Hengen