[sf-lug] semi-OT: help with dying disk

[matt.price at utoronto.ca]

hi folks,

i htink i may have asked a similar question before, since this is the  
second time in 3 months that i've had a disk drive die, and no, i  
apparently still haven't learned my lesson.

the hard drive in my laptop is dying, with messages of this ilk:

-----------
root at ubuntu:~# tail /var/log/messages
Mar 14 02:28:55 ubuntu kernel: [17232.876000]         08 21 3f e0
Mar 14 02:28:55 ubuntu kernel: [17232.876000] sd 0:0:0:0: [sda] Add.  
Sense: Unrecovered read error - auto reallocate failed
Mar 14 02:28:55 ubuntu kernel: [17232.876000] end_request: I/O error,  
dev sda, sector 136396768
Mar 14 02:28:55 ubuntu kernel: [17232.876000] ata1: EH complete
Mar 14 02:28:55 ubuntu kernel: [17232.876000] sd 0:0:0:0: [sda]  
195371568 512-byte hardware sectors (100030 MB)
Mar 14 02:28:55 ubuntu kernel: [17232.876000] sd 0:0:0:0: [sda] Write  
Protect is off
Mar 14 02:28:55 ubuntu kernel: [17232.880000] sd 0:0:0:0: [sda] Write  
cache: enabled, read cache: enabled, doesn't support DPO or FUA
Mar 14 02:28:55 ubuntu kernel: [17232.880000] sd 0:0:0:0: [sda]  
195371568 512-byte hardware sectors (100030 MB)
Mar 14 02:28:55 ubuntu kernel: [17232.880000] sd 0:0:0:0: [sda] Write  
Protect is off
Mar 14 02:28:55 ubuntu kernel: [17232.880000] sd 0:0:0:0: [sda] Write  
cache: enabled, read cache: enabled, doesn't support DPO or FUA
-----------

i'm currently at this point:
i've dug up an ubuntu live cd & managed to run fsck on the root  
partition on this machine.  there were lots of errors but i just said  
yes to everything it wanted to do and in the end, when i mounted the  
repaired partition, there were only a couple of dozen files in the  
lost+found.  so i immediately started rsyncing to my backup (too  
late!! i know)& have found that in general, i can go for about a  
gigabyte before getting these errors, at which point rsync eventually  
dies.  i have this feeling (likely wrong) that it doesn't always stop  
in the same places -- that is, that it's not necessarily that the disk  
has a hole where the file's supposed to be, but that it's just tired.   
   so as regards recovery, i wanted to know whether there is some kind  
of strategy for reducing the strain on the disk -- it feels to me as  
though it's slowly dying but it might last longer if i treat it gently  
(i have no idea whether this is remotely true or even possible).

that's the most important question.

then i have a second one, regarding a new disk.  from the looks of it,  
$150 will now buy either 200 gigs of 7200 RPM  2.5" disk, or 250 gigs  
of 5400 RPM.  any idea how the speed difference is likely to affect  
both speed and power consumption on my laptop?  this is a dell d820  
laptop with a core duo cpu, so it's fairly quick by my standards, but  
of course i wouldn't mind it being faster; however, it's also a  
terrible power hog under linux, currently (with what i believe is a  
5400 rpm disk) barely staying up for an hour on battery power.

so i wondered, any comments on the likely speed/power tradeoff, and  
also any hints about increasing disk lifetime?  this is the first  
laptop drive that's failedo n me, and i'm wondering whether it's just  
bad luck, a bad manufacturer, or possibly some defect in the way that  
disk access is managed under recent versions of ubuntu.

so thanks much!!

matt