I had a similar problem (also with esata sheevaplug) where the fsck of the root fs failed. It would run fsck.ext4 but the rootfs s ext3. So it would choke.
You don't specify which disk is failing so this might be your problem.
I 'fixed' it by adding a line in fstab mounting roots with 0 0 options at the end (copy the entry out of fstab).
I don't know why that should affect it, but it worked after that and I didn't do anything else.
here is the complete error message, I don't see which disk is failing
Usage: fsck.ext4 [-panyrcdfvtDFV] [-b superblock] [-B blocksize]
[-I inode_buffer_blocks] [-P process_inode_size]
[-l|-L bad_blocks_file] [-C fd] [-j external_journal]
[-E extended-options] device
-p Automatic repair (no questions)
-n Make no changes to the filesystem
-y Assume "yes" to all questions
-c Check for bad blocks and add them to the badblock list
-f Force checking even if filesystem is marked clean
-v Be verbose
-b superblock Use alternative superblock
-B blocksize Force blocksize when looking for superblock
-j external_journal Set location of the external journal
-l bad_blocks_file Add to badblocks list
-L bad_blocks_file Set badblocks list
fsck died with exit status 16
I tried it with:
/dev/sda1 /srv [b]auto[/b] defaults,noatime 0 1
and didn't get an error. Unfortunately the disk isn't mounted :-(
Can you please post your fstab? My initial fstab was emtpy, therefore I have no idea how you added the rootfs ...