I've been given a Packard Bell MH35 laptop that "quit working" some time ago - indeed Windows Vista bluescreens on boot. I immediately ran a Live-CD distro, but it gave "revalidation failed" errors at boot and refused to work properly. Running the all_generic_ide boot parameter as per this made the live boot with no errors, but when I installed Parsix on the hard disk and it started booting from that the parameter fix no longer worked. It didn't always do the error at the same point during the boot process.

I spent some time swearing at this, then because the source of the problem seemed to be hard-disk related I swapped the drive with a spare. Problem solved, computer boots fine.

Bad risk, right? Except if I hook it up to any computer with a SATA-to-USB adapter it seems to be working perfectly. No transfer errors, no bad sectors that a badblocks scan can determine.

I'll put the "bad" disk in an enclosure and use it to shuffle data, but I'm still curious - what can cause a disk to no longer work as a boot device, but work perfectly externally?

Hi,

'bad sectors' can cause problem(s). If you get a head hit then the drive can fail. Most head crashes are destructive and the drive is then unusable. Sometimes 'bad sectors' can be caused by electronics malfunctioning due to power issues. Leaky capacitors can cause issues.

If you value your data, I would be sure to diagnose the problem. Not place a known problem disk in a enclosure to move data that could be 'garbage' data at some point in time.

Try to use the disk manufactures diagnotic set or get;
UBCD Ultimate Boot CD <- 'UBCD allows users to run floppy-based diagnostic tools from most CDROM drives on Intel-compatible machines, no operating system required. The cd includes many diagnostic utilities.'
or
SystemRescueCd <- 'is a Linux system on a bootable CD-ROM for repairing your system and recovering your data after a crash. It aims to provide an easy way to carry out admin tasks on your computer, such as creating and editing the partitions of the hard disk. It contains a lot of system utilities (parted, partimage, fstools, ...) and basic tools (editors, midnight commander, network tools).' + 'Online-Manual

The above links and others can be found at 'Slackware-Links'. More than just Slackware® links!

I sure as hell won't be using it to move important data.

I'm aware of the problems caused by bad sectors, having encountered plenty, but they don't usually result in this behaviour, and badblocks usually catches them. Admittedly I haven't tried a destructive test (badblocks gets seriously slow when doing that).

I'll clarify one thing: when the computer runs with the "bad" drive in, the simple fact that the disk is plugged in causes "revalidation failed" errors. When booting a live-CD the hard disk isn't accessed at all, so there's no way bad sectors could be influencing the boot sequence.

I'm suspecting something in the disk's electronics, but then it shouldn't be working on a USB adapter either...

Another reason is drive levels. Putting it at it's simplest, highs might not be high or lows may not be low when they are sampled by whatever is reading the circuit. As you speed up, the chance of this type of error increases. A drive caddy has controller beside drive and not loaded by anything else, and so things might perform better.

Hi,

Sorry, but the kernel will attempt to recognize or init devices be it for a LiveCD or install. Look at: Linux Kernel Interactive Map

Silicon does not heal! Platters do not heal!
Your device, so use it as you will. Just expect issues.

I still suggest that you diagnose the drive first with manufactures diagnostic set or one of the before mentioned LiveCD. It's one thing to speculate and another to confirm there is a problem or not.

My