You say that you have a terminal connection in to the ALOM, so I assume your server is a V240 or similar. To get to the ok prompt from there:

1. Exit out of the console by typing Enter # . (that's the enter key, followed by hash, followed by dot). You should now be at the sc> prompt.
2. Send a break signal by typing break -y
3. Return to the console with console -f

As Iain says, the console messages indicate that the server is trying to boot off the network. You can use the boot command to manually boot off a disk or cdrom. You should also change the default boot device. At the ok prompt you can do this with the printenv and setenv commands, or alternatively you can boot into Solaris and do this with the eeprom command.

For some reason, c2t5d0s4 (/d001) and c2t5d0s5 (/d002) are set up as one-way mirrors in SDS. Perhaps someone forgot to metattach another disk at some point?

To accomplish what you want, there are two methods.

Method 1

As you suggest, dd could be used. I would first verify that you don't need the data on c2t6d0s6 by mounting it and reviewing the filesystem contents.

mount /dev/dsk/c2t6d0s6 /mnt

You also have two small partitions at the start of the disk. Check with metadb that these aren't required by SDS. If they are listed and there are partitions on the other disks in the metadb, remove them:

metadb -d c2t6d0s0
metadb -d c2t6d0s1

Then you will be able to use dd to clone:

umount /d001
umount /d002
dd if=/dev/rdsk/c2t5d0 of=/dev/rdsk/c2t6d0

Method 2

As you already have SDS configured you can use this to complete the mirrors.

First you need to copy the partition table:

prtvtoc /dev/rdsk/c2t5d0s2 | fmthard -s - /dev/rdsk/c2t6d0s2

Then create metadevices:

metainit d72 1 1 c2t6d0s4
metainit d82 1 1 c2t6d0s5

Then attach these do the existing mirrors:

metattach d7 d72
metattach d8 d82

Warning: metadevice d71 already has errors logged against it by SDS and has been placed into maintenance. It might refuse to copy this partition.

Periodically check that the mirrors are syncing:

metastat

You'll get a progress next to each submirror that is rebuilding. The State: field will say Okay once rebuilding has finished.

Removing the old drive

Disconnect each partition that is mirrored.

metadetach d7 d71
metadetach d8 d81

I can't remember if Solaris 8 has cfgadm or not, but if it does, run:

cfgadm -al

to check which device you want to remove (probably c2::dsk/c2t5d0), then unconfigure it:

cfgadm -c unconfigure c2::dsk/c2t5d0

It will then be safe to remove it.

HOW CAN I VERIFY THAT /d001 and /d002 are the ONLY THING MOUNTED FROM THE OLD DRIVE?!

Simple: They're the only partitions on the disk. (Slice 2 is the whole disk, not an actual usable partition.)