Can't exec /bin/sh for single user

Question

Hi,
When I boot up my iMac G5 it sits on the gray screen with the apple and spinning "doing something" icon, and then goes to a terminal window telling me:
"can't exec /bin/sh for single user: Input/output error"
It started doing this last night after multiple beachball of death situations. Anyone have any ideas? Or is it time for this old machine to be put out to pasture?
Thanks
Mungo

Answer 1

Hi Mungo,
invalid key length is a serious issue that can sometimes be fixed by "heavy duty" utilites like DiskWarrior and Drive Genius.
If you don't have enough room to re-install the OS, though, you have seriously overfilled it and they may not be able to deal with the problem either.
You should always aim to keep at least 15% free space on the drive, preferably more. On my 250 Gig internal drive, for example, I see the beginning of stability and speed problems when I get down to below around 30 gigs of free space. It varies a bit depending on what you use your Mac for, but my own preference is to always aim for 50 Gigs free on this 250 Gig drive.
You have to fix the "keys out of order" problem before you even think of re-installing the OS.
The best solution is to reformat the drive. It is unlikely that it actually needs replacing. However I still think you should buy another drive, but an external one, if you don't have one already.
My approach to your problem would be:
1) Go and buy a nice big external firewire drive if you don't have one already (ideally at least twice the size of your internal).
2) Install OSX on the external drive (You may want to partition it into two volumes first, keeping one partition to store a "cloned backup" of your internal and one for general usage, overflow storage, etc)
3) Boot from the external HD and copy across your precious stuff from the internal drive to the external. (If you have created two partitions on the external you could use the excellent utility "SuperDuper" to "clone" the internal to the second partition - the one witout the OS installed on it)
4) Reformat the internal drive, preferably using the single "zeroing" option.
5) Re-install the OS and software on your internal drive
6) Copy back your data (documents, music, movies etc) to your internal but make sure you leave plenty of free space on it. If you have a large music library , or lots of movies, for example, you might want to keep them on the external, rather than putting them back)
7) From now on use one partition of your external drive for regular "cloned" backups of the internal and the other for general storage overflow etc.
Cheers
Rod