When your hard drive crashes there is hope in most cases.
Problem
窶｢ The computer will start but won't get past lighting up the screen.
窶｢ The computer will start but a disk with a (?) or (x) in it comes up.
窶｢ The computer boots up but you can't find the hard drive on the screen.
The goal is to get back your hard drive. The secondary goal if this is not possible will be to get back your data.
Read on.
HD Crash: 1st Attack
1. Shut down your Mac and anything connected to your Mac. Wait a few minutes and restart.
2. Hold down the shift key during restart. This will disable most extensions (small programs that add functionality to the computer but can do without). This only works with System 7. If you are running System 6 see the appendix for "Extensions" If you don't know which System you are running see the appendix "Operating Systems".
3. Start up from your emergency disk (or disk tools that came with your computer) and run Disk first aid
4. Start up from your emergency floppy (appendix, software tools) and launch SCSI probe, available from a user group or online service. If it can see the disk but can't mount it then you have a bad driver on the disk. Update the driver using "Apple HD SC Setup" from you emergency disk.
5. Disconnect all SCSI devices (hard drives) if you have any external ones connected to your Mac. (Be sure they are turned off first). Repeat steps 1-3.
6. If the disk still doesn't work then rebuild the desktop (appendix, Rebuilding the Desktop).
7. Reset your PRAM (appendix Resetting PRAM)
HD Crash: 2nd Attack
If the previous chapter didn't help the plot thickens..
1. Restart your computer from your emergency floppy.
2. Run Apple HD SC Setup
3. Run the formatter (not initialize!) and see if the software recognizes your drive at the SCSI address (in other words is the computer letting you see the drive).
4. If..you have another formatter, try it.
5. If you have a data recovery program like Mactools or Norton's Utilities then try to repair the drive with them.
6. Run Disk First Aid a few more times alternating with the data recovery program.
HD Crash: Final (sigh...)
Okay you now have a problem...The following suggestions are not easy or practical for many people but I mention them because they are options.
1. If your drive is external connect it to another Mac and try it.
2. If your drive is internal you can remove it and connect it in another Mac and try it. (appendix, hard drive removal). Try all recovery methods with the drive in another machine.
3. If all else fails you have to decide if the data on your drive is worth paying $100-$300 to recover. If you think it is then check the appendix for Data recovery services.
SCSI
SCSI (Small Computer Interface System) was for a while a fairly fast interface system for hard drives and some other devices. It was adopted in the Macs because of its ease of use. Macs have been noted for their "plug and play" ability. With other interface systems, like those used in the IBM compatable world, attaching a hard drive could become a major installation problem with lots of software installation hassles. This has changed recently though with newer types of interfaces coming out, and the future holds even bigger and better types.
Symptoms of a SCSI problem
窶｢ You just get a question mark on the screen at startup time.
窶｢ The hard drive doesn't mount so you never see the icon on the screen.
窶｢ Multiple hard drive icons show up.
窶｢ SCSI drives that work intermitently.
The best, more easily available tool to use is SCSI Probe. It is available from online services and is installed in the system folder. SCSI Probe will show any drives that are not "dead" and will sometimes let you mount them.
There are other commercial programs that will assist you in finding and repairing your hard drives some of them can indicate SCSI problems and advise you on them. They are discussed elsewhere.
The Cables
Of course you did try another cable didn't you? Yeah, they are expensive but if you can get hold of one it could save you a lot of time and effort. Never remove a SCSI cable from your computer while it or any of the peripherals are connected to it. The SCSI cable has lots of wires in it so the possibility of one breaking is not out of the question.
Keep the cables or chain of cables to under 16 feet. Anything much over that will cause flukey behavior. In fact keep the chain as short as possible.
ID Conflicts
Your internal hard drive (if you have one) is set at #0. Each SCSI device has an ID. You can't have two devices with the same ID. Confusion will result. The other ID's are 6 -1. Your computer looks for each one of them in that order when it starts up.
Most drives have a small switch on the back that allows you to click up and set the ID#. Some (please try to avoid them) drives have an internal set of dip switches that are used to set the ID. You have to configure several switches in a pattern indicated by the instruction manual that came with the drive.
Terminators
Terminators connect to your hard drive (or other SCSI ) peripheral at the beginning and end of the SCSII chain. They come in different varieties but they basically look like a SCSI connector without the cable. They are a resistor that absorb the SCSI signal and don't let it bounce back (ringing) to the computer.
Your internal hard drive is already terminated so that's the one at the beginning of the chain. It doen't matter how many devices you have attached but you need to have the last one terminated also, even if only one is connected.
Do you have a Mac Plus? It doesn't have an internal terminator so you must terminate the first device on the chain also.
