14 May
2002
14 May
'02
2:46 p.m.
Well, today I lost the first drive in years due to a head crash. The data
it contained wasn't extremely important, since I can reconstruct it given
time, but sadly, I didn't have a listing of the drive's contents.
After getting the air reasonable clean in a makeshift clean-room, I took a
look at the platters, and found the topmost surface of the upper platter
is the one that took damage. (If I decide to do any serious work on the
drive, I'll have to build a clean-box...)
I'd like to get the drive to a state where I can at least get a directory
listing, but the data it contained isn't worth what it would cost to send
it off for 'professional' recovery, especially since those shops tend to
charge a small fortune for Linux e2fs formatted drives. I have another
drive that is identical to the one that failed, so I have donor parts to
repair it with. The second drive has a bad head, but it affects one of the
lower platters. I've never had to replace a head before, so I'm looking
for advice, or even a step by step guide to replacing it.
The drives are both a Conner CFS1275A, 1.2GB, 3 platters, 6 surfaces. I'm
starting to suspect the top surface of the upper platter is the servo
surface, due to the behavior of the drive when it failed. Can anyone
confirm if this is the case, or if these type of drive even use a servo
surface? The 1275A doesn't quite yet meet the 10 year rule, but with all
the experts here, I figure someone is bound to know more about these
drives then I currently do.
-Toth
14 May
14 May
7:26 p.m.
A non-text attachment was scrubbed...
Name: not available
Type: text
Size: 1700 bytes
Desc: not available
Url :
http://www.classiccmp.org/pipermail/cctalk/attachments/20020515/c99f9421/at…
15 May
15 May
5:21 p.m.
On Wed, 15 May 2002, Tony Duell wrote:
That makes sense. Do you think these drives stripe data across the
platters, or would data be more "randomly" placed? Would a drive normally
start from the top side of the top platter and go towards the bottom of
the stack, or do some drives use a more "random" scheme? I'm wondering if
there is anything left to recover with one side of one platter badly
damaged.
> repair it with. The second drive has a bad head,
but it affects one of the
> lower platters. I've never had to replace a head before, so I'm looking
> for advice, or even a step by step guide to replacing it.
I'm starting to think the head assembly of that second drive might not be
bad. The platters seem to spin at too high of speed, which makes me wonder
if the spindle motor is bad. That drive's logic board checked out ok on
yet another drive, so I know that much of it is good. It also (according
to the date written on it) failed right at 2 years after it was
manufactured. I think those particular drives actually had a 3 year
warranty on them, so I guess someone didn't know to send it in for a
replacement (it was marked 'bad' when I got it.)
The drives are
both a Conner CFS1275A, 1.2GB, 3 platters, 6 surfaces. I'm
starting to suspect the top surface of the upper platter is the servo
surface, due to the behavior of the drive when it failed. Can anyone
confirm if this is the case, or if these type of drive even use a servo
My guess is that these drives use 'embedded servos'. Basically, the
servo bursts are in the sector headers on each surface -- there is no
dedicated servo surface. The DEC RL01 is an early and understandable
example. So if your top platter is unreadable, the servo will not lock
when you try to read that surface, and this may be enough to cause the
drive to spin down. I have to tell you that what you are doing is a
'challenge'. The
flying height on such drives is much lower than on the older
winchesters that some of us have repaired at home (== you need a much
better 'clean box' to avoid further headcrashes). Also, there's
generally no procedure for aligning the head. The heads are assembled
at the factory, then the head arm is connected to a formatter
(basically a very accurate stepper system :-)), then the tracks and
servo bursts are written. There is no easy way to replace a head and
get it aligned with the existing tracks.
I'm not one to bow out to such a 'challenge', though if I don't feel
comfortable in doing the work, I'll sometimes set things aside until I
have more information or better tools to work with.
How clean will the air need to be? Since I don't plan to use the drive
long-term, as long as it will hold up for about an hour or so, I'll be
happy. What about dust and debris caused by the initial head crash? Is it
likely the scratches on the platter will damage a new head, or is there
something I'll need to do to prevent that?
Would it be possible to replace the entire head assembly with that from
another (possibly working) drive? Would that have a better shot at keeping
the heads aligned? Anyone have a dead CFS1275A that just has a damaged
logic board? (Preferably one of the earlier versions with the green Conner
sticker, and close to a 9532 date code.)
I started going through the classiccmp archives for posts on this topic,
but it is very hard to sort out all the bits of information. Is anyone
aware of a faq/guide online somewhere that covers this sort of thing?
-Toth
7:36 p.m.
A non-text attachment was scrubbed...
Name: not available
Type: text
Size: 3847 bytes
Desc: not available
Url :
http://www.classiccmp.org/pipermail/cctalk/attachments/20020516/fa46e9e7/at…
8281
days inactive
8282
days old
3 comments
2 participants
participants (2)
-
ard＠p850ug1.demon.co.uk -
tothwolf＠concentric.net