The density of bits on the magnetic surface has exploded since disks were 5-10MB, especially in the last 10 years. Other storage technologies haven't been able to keep up. You can't even back up your disks any more because they're so huge. Ok there's DLT - far too expensive for home use, and another disk. DVDs only cut it up to a limit. A 200GB hard disk is over that limit. The high magnetic bit density implies it's unreliable. Other factors like mechanical failure and had crashes haven't changed in 20 years. And the lot has got cheaper - you couldn't buy any size hard disk for 200 bucks 20 years ago. Cheaper bigger better faster cheaper -> unreliable. The fact that disks blow up hasn't changed a bit.
Forget about that bad sector scanning and bad blocks handling - it's all in the disk already. Youy can't even influence it. From my last discussion about how to make a program which salavages as many still-readable sectors as possible from a damaged disk it emerged that when the disk returns an I/O error, it has already tried several hundred times. No point trying a second time yourself, unless you alter other parameters - head positioning geometry via temperature for example. However the more you try and read faulty areas, the more you risk taking even more particles off the surface and spreading them around. Disks now have more or less substantial integrated self-monitoring (this SMART stuff). They can measure whether head positioning is mechanically wonky, whether spin-up is impaired, and similar things. You can kickstart these tests externally too. If disks go *bang* and keel over dead then there's no warning. I've also had plenty of warning from the disks's selftest, more of a problem is interpreting the signs I found. You want package smartmontools from sourceforge. Volker -- Volker Kuhlmann is possibly list0570 with the domain in header http://volker.dnsalias.net/ Please do not CC list postings to me.
