Vendor Partitions

I just changed my OS so I don't have all of my mails.

Andrew, 
you mentioned something about wanting a clean interface for partition codes. I 
have
some thoughts on the Vendor Partitions (VP) of which the Compaq Diagnostic 
Partition is one
example. 

I will never use parted to create a VP. If I somehow mess up a VP I'll use the 
Vendor provided
disks to repair/recreate the VP. The utility disks will create a new partition 
table, a new VP,
a filesystem (or some other datastructue) on the VP and populate the 
filesystem.  

In most cases (I think) the Vendor has never specified what format the VP has. 
They may change
it. This doesn't matter. I would treat the VP as a blob. The internal format is 
irrelevant. I
would never waste my time reverse engineering the format. 

At the moment the on time that I worry about the VP is when 

1) I want to partition my harddrive (I don't want to destroy the VP) 
2) I want to back up my computer (I have to back up the VP).

To solve 1) you might have parted check to see if the drive has a VP. If it has 
do not wipe the
partition table and do not remove the VP. Protect the VP from being 
overwritten. This isn't
really that important. Whatever precations you take in parted the VP can still 
be destroyed by 
some other program. 

2) is more important IMHO. Whenever I install Linux on a computer with a VP i 
get very nervous.
If I fsck up I have a lot of work ahead of me. I took me half a day to create a 
new VP on my
old Compaq Laptop when I messed up. (The actual procedure took 15 minutes. 
Finding the damn
restoration disks on the website took forever :( )

Currently I have 2 options to back up my VP. 

dd the first 5 megs of my drive. (This probably only works for a Compaq VP 
since it is normaly
a < 2 meg partition located at the beginning of the drive. ) To restore just dd 
back the data.
Not very elegant. 

or 

Use parted to copy the partition. To restore the computer do the following. 
Create a partition
table with parted or fdisk. Use parted to copy back the partition. Use fdisk to 
set the 
partition code. Not very elegant either.

What I would like is something like

parted save-vendor-state /dev/hda ~/backup
parted restore-vendor-state ~/backup /dev/hda

This way you can treat all VPs the same. 

When it comes to the other partition codes I don't know what to do. I guess you 
could talk to 
the Hurd people and convince them to use a Linux partition :) 


I think the reason you are having a hard time to come up with a clean way to 
treat partition
codes is that there isn't any one way. Diffrent partitions belong to diffrent 
classes. VPs
being one of them. Normal filesystems is another This class can be divided into 
the the class
of fs which parted can create and the class of fs that parted cant create. ( I 
don't think it 
is desirable for parted to be able to create every fs known to man. ) Things 
like the Partition
Magic partition type fall into a third class. There might be more. 

To get clean code you will (probably) have to deal with the classes diffrently. 

Ok thats enough random ramblings for one night :)
--
Henrik Treadup 
henrik.treadup@xxxxxxxxxxxxxxxxxx