Quote Originally Posted by saikee

Your extended partition behaves slightly different to my prediction. This is possibly due to the way you created it as the extended partition can have one partition type. By hiding it the partition type just has "1" added to the type number and this should show up in the "fdisk -l" command in root console.

Can you list the "fdisk -l" output (in root console) before and after hiding sda1?
I tried to follow your instructions in your post to me that showed how to make grub hide / unhide as best I could. The results are posted below.

grub could not/would not allow a parameter as sda1, per your post, quoted above. I have pasted what I could get grub to do.

grub> hide (sda1)
Error 23: Error while parsing number

grub> hide (sda1,1)
Error 23: Error while parsing number

Then I looked at the geometry as a double check to find sda or sda1

grub> geometry (hd0)
drive 0x80: C/H/S = 38913/255/63, The number of sectors = 625142448, /dev/sda
Partition num: 0, Filesystem type is ext2fs, partition type 0x83
Partition num: 1, Filesystem type unknown, partition type 0x82
Partition num: 2, Filesystem type is ext2fs, partition type 0x83

grub> geometry (hd1)
drive 0x81: C/H/S = 2434/255/63, The number of sectors = 39102336, /dev/sdb
Partition num: 0, Filesystem type is ext2fs, partition type 0x83
Partition num: 2, Filesystem type is ext2fs, partition type 0x83
Partition num: 4, Filesystem type unknown, partition type 0x82
Partition num: 5, Filesystem type unknown, partition type 0x82
========================================

WITH (hd0,1) HIDDEN, the output is:

NEXT, the above mistake made me think you meant (hd0) so I:

grub> hide (hd0,1)

and the output of fdisk -l is:

mark@Lexington:~$ sudo fdisk -l

Disk /dev/sda: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000080

Device Boot Start End Blocks Id System
/dev/sda1 1 1785 14337981 83 Linux
/dev/sda2 1786 2040 2048287+ 92 Unknown
/dev/sda3 * 2041 2306 2136645 83 Linux

Disk /dev/sdb: 20.0 GB, 20020396032 bytes
255 heads, 63 sectors/track, 2434 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000080

Device Boot Start End Blocks Id System
/dev/sdb1 1 2040 16386268+ 83 Linux
/dev/sdb2 2307 2434 1028160 5 Extended
/dev/sdb3 * 2041 2306 2136645 83 Linux
/dev/sdb5 2328 2434 859446 82 Linux swap / Solaris
/dev/sdb6 2307 2327 168619+ 82 Linux swap / Solaris

=====================

and then I

grub> unhide (hd0,1)

with state as NOT hidden the output of fdisk -l, below:

mark@Lexington:~$ sudo fdisk -l

Disk /dev/sda: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000080

Device Boot Start End Blocks Id System
/dev/sda1 1 1785 14337981 83 Linux
/dev/sda2 1786 2040 2048287+ 82 Linux swap / Solaris
/dev/sda3 * 2041 2306 2136645 83 Linux

Disk /dev/sdb: 20.0 GB, 20020396032 bytes
255 heads, 63 sectors/track, 2434 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000080

Device Boot Start End Blocks Id System
/dev/sdb1 1 2040 16386268+ 83 Linux
/dev/sdb2 2307 2434 1028160 5 Extended
/dev/sdb3 * 2041 2306 2136645 83 Linux
/dev/sdb5 2328 2434 859446 82 Linux swap / Solaris
/dev/sdb6 2307 2327 168619+ 82 Linux swap / Solaris

Is there a way to make grub hide or unhide a device called: sda? or sda1? Is that what you want?