Question concerning Raid Manager default partition table

[James McPherson - Customer Technical Support Engineer]

> Hi Andreas,
> 	Well, that's an idea, but I've just
> made it a habit never to use slice 2, especially
> as a mounted partition (although I must admit
> that I do use it when there's a specific command 
> requirement to do so).  It's hard for me to 
> break a habit once I pick one up :-)
 
> -----Original Message-----
> From: Andreas Sindermann [mailto:sinder@thp.Uni-Koeln.DE]
> Carolyn Chandler writes:
>  > Hi,
>  > 	I've noticed that the partition table for drives configured with
>  > Raid Manager always consists of 2-128MB partitions on slices 0 and 1,
> while
>  > the rest of the free space is given to slice 6.  I was wondering if
> anyone
>  > knows of a reason for this...are the 2 128MB partitions really used for
>  > anything?  Can the LUNs be repartitioned to use this extra 256 MB?
> 
> Why not simply use slice 2 which covers the whole LUN?

The short answer to this is, because if you do then your configuration is not 
supported. The longer answer is that there are some applications (dd, backups 
etc) for which you need to be able to grab the _whole_ disk all at once without 
worrying about partitions. 


>From the "Ten common backup/restore related questions" doco on sunsolve (faq 
2084):

---
7.  Is it was possible to do an image backup of an entire disk
    using the dd command?

    With the standard layout, Solaris continues in the tradition of the
    Berkeley based operating systems where partition 'c' (slice 2) actually
    represents all of the blocks on the disk drive.  You should not newfs
    this.  The newfs would create a file system that spans the entire disk
    drive.  If you did this after having newfs other slice, you would destroy
    information on these other slices.  The "dd" command can backup the
    entire disk using slice 2.  It looks like this

       # dd bs=80b if=/dev/rdsk/c0t3d0s2 of=/dev/rmt/0m

        Where:
            bs  stands for blocksize
            if  stands for input file
            of  stands for output file
---


So there you have it - history ;)

cheers,
James C. McPherson

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