[Coco] Drive freezing / data reovery (WAS: Re: Need to know

[Gene Heskett]

On Sunday 05 August 2007, Briza wrote:
>Hi Gene.
>
>You mentioned this in your last post.

And your email agent's quoting is broken.  The text below that I wrote originally, should have two >> in front of each line.  This is so that in long 'conversations', folks can see who wrote what.

>And this is a good excuse for me to jump in and emphasize that in either
> cable style, the drive to be used as the master drive MUST be on the end of
> the cable as it does the scsi-like and _required_ termination. 
> Automatically, you don't see it, but its there.  The slave if used must
> then be on the middle connector since 'slaves' don't enable their
> terminations.  In no case can you put a master programmed drive on the
> middle connector and leave the surplus cable hanging in the breeze, its not
> a matter of if your data gets scrambled, but when, and its usually sooner
> than later.
>
>Sitting here reading this thread, I'm wondering if that's what actually
>happened here.  Decent cabling, but miss-configured keeps raising the
> thought in my mind.  I have had a couple of really cheap cables go toes up,
> but more than likely in the one case I have right now, the chipset simply
> cannot handle two drives on the same cable, which is the case in the box
> that runs my milling machine.  I've had 3 drives and 3 cables in that box
> trying to make it handle two drives on cable 0, can't be done, both drives
> will get trashed in pretty short order.  Just one drive and its been fine
> for over a year.  EMC doesn't need the other 60GB of drive anyway.
>
>Well I have to say your right. I never realised it. But my Master was in the
> Middle of the cable. And my old Win98se drive was on the end cable. No
> wonder sometimes the Win98se would bootup and ignore the Master drive(XP,
> As it was in the middle). So this and the faulty cable would surely do as
> you say. And start to slowly corrupt the Boot track on my XP drive. So when
> I hook up both drives again. The Master drive will be on the End. And the
> Slave will be in the middle. This should stop the slow corruption process.

Sometimes its not so slow. :(

> Also to the Fellow coconut who mentioned. Is the IDE cable a DRIVE SELECT
> CABLE. Not by the looks of it. Looks standard to me. Also both drives were
> jumpered. XP(Master), Win98se(Slave).

Drive select cables generally have a different color plastic for each 
connector.  With those cables you can set both drives to CS, and the 
master will be whichever drive is on the end of the cable.  The longer 
end of the cable goes to the motherboard of course.

The relative lack of publicity given such important details has a tendency 
to get under my skin a bit, as it allows the creation of exactly the sort 
of a situation that led to this.  Hopefully you can re-ghost the XP drive, 
either from the backups you were supposed to burn, or from the hidden 
partition that XP keeps an image of itself in.  I expect if the hidden 
partition is used for recovery, your data on the drive will be gone however.

Be aware that in modern hard drives, the formatting is a factory setup 
operation only, and all you and I can do is re-write the filesystem which 
uses whatever scheme we choose to keep track of where things are.  The 
only time that you issue a read sector x and get a different physical 
sector is if the drive has previously had trouble reading sector x, and 
had a certain number of failures to get a good checksum, then it may 
re-assign sector x to one of its many spare sectors and copy as much of 
the bad sector as it can recover from the original sector x to the new 
one it has assigned.  This is all done in relative silence without 
reporting it to you in any great detail.  I suspect that windows just
ignores it.

Most drives will give you a report of such stuff if queried correctly.
Here in linux, we have a badblocks program that can be used by 
knowledgeable people to assess/adjust these internal re-assignments, but 
its also something I've not resorted to, but I do occasionally inspect 
the output of our 'smart' daemon utility, which can extract all sorts 
of data from a drive using smartctl.  Like this:

[root at coyote 6309l3]# smartctl /dev/hda -a
smartctl version 5.37 [i686-redhat-linux-gnu] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

=== START OF INFORMATION SECTION ===
Model Family:     Western Digital Caviar SE family
Device Model:     WDC WD2000JB-00EVA0
Serial Number:    WD-WMAEH2782398
Firmware Version: 15.05R15
User Capacity:    200,049,647,616 bytes
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   6
ATA Standard is:  Exact ATA specification draft version not indicated
Local Time is:    Sun Aug  5 07:56:03 2007 EDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

and I'll not bore the list with all of it as its the equ of about 3
pages of paper.  The only interesting statistics poem is this one:

(beware long lines here)

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   200   200   051    Pre-fail  Always       -       0
  3 Spin_Up_Time            0x0007   125   124   021    Pre-fail  Always       -       4250
  4 Start_Stop_Count        0x0032   100   100   040    Old_age   Always       -       95
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   253   051    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   068   068   000    Old_age   Always       -       23600
 10 Spin_Retry_Count        0x0013   100   253   051    Pre-fail  Always       -       0
 11 Calibration_Retry_Count 0x0013   100   253   051    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       92
194 Temperature_Celsius     0x0022   113   253   000    Old_age   Always       -       37
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0012   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0012   200   200   000    Old_age   Always       -       0
199 UDMA_CRC_Error_Count    0x000a   200   253   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0009   200   155   051    Pre-fail  Offline      -       0

SMART Error Log Version: 1
No Errors Logged

So this drive is in good shape, with a power_on hours of 23600 so far.
This box run 24/7 unless I'm doing things to the hardware.

>laters
>
>Briza

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If you would know the value of money, go try to borrow some.
		-- Ben Franklin