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 Post subject: Need Help Understanding Quantum AS BAD SECTORS - G-list :
PostPosted: March 23rd, 2015, 18:44 
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Need some help from someone whod knows very well Quantum AS drives, please ...
I can't undrestand this :

Start with a clean secure erased and S.M.A.R.T. cleared HDD - Quantum AS.

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I attempt to do a read long command by C/H/S and get sector 1 with the ECC bytes at the end - 00 01 01 00 00 00 23

On a cleared drive all data is 00 and the 4 relevant byte of ECC is 00 while FF is ignored.

Now i write to the sector (edit buffer and send it to the drive with write long).

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So i'm going to write to the drive sector data but will maintain the same ECC (will write long with wrong ECC) instead of write and calculate new ECC. This will produce a BAD SECTOR :

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So far so good, now let's do a normal READ on the sector with wrong ECC :

As expected i get error and uncorrected :

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Now the "strange" thing, the drive puts the sector on the G-List and consider it as relocated and pending for relocation at the same time !!!

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I didn't attempt to write to the sector, i've just read it, and the drive placed it on G-List but for some reason the sector is on G-List and it's not swapped by a spare :

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Now it even gets more strange ..... If i WRITE back to the sector with correct data ....
Let's say i will clear the data on the buffer and write back to it :

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The sector disapear from G-List and Relocation Count on S.M.A.R.T. and pending Relocation as well !!!!!

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Note that I DIDN'T CLEAR S.M.A.R.T. neither cleared G-List !!!!

The fact that i was able to write back to the sector and the fact that it "disappeared" from G-List lead me to believe that the sector was NEVER swapped by a spare to start with, so why the hell was it on G-List ?

I was under the impression then when the drive relocates the sector by swaping with a spare only then the "bad" is placed on G-List ...

So how could this sector be on G-List and yet be accessable (original one and not the spare) and why did a "write" with correct ECC corrected the sector and removed it out of the G-List ?

Maybe this is how old drives got fixed with stuff like spinrite, if a "bad" sector or a sector without correct ECC gets read and the data is retrieved and written again, the ECC will be corrected and it looks like that at least on those old AS Quantum drives the "bad" sector is removed from G-List !!!!

This is really strange, because i was under the impression that when a sector was added to G-List unless one would use vendor specific commands to remove it from G-List or to clear G-List it would stay there for the rest of the life of the drive and the relocated sector would point out to a spare ...


Need help understanding this ....

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 23rd, 2015, 18:49 
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By the way, this test was done on Quantum Fireball AS and prior to starting the test i've issued the "Super Off" to make sure that the drive was not on special mode and all of the used commands were standard ATA ones ...

Doesn't make sence to me that the sector was added to G-List, was not swapped by a spare even when it was on G-List and then it was removed from G-List and from relocation count when new data (correct ECC) was written to it.

Attachment:
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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 24th, 2015, 16:16 
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INTERESTING FINDING :

I've written something to LBA 0 - Sector 1 in C/H/S to the drive.

1 - Add first 3 sectors to G-List and upload to the drive. Power off-on :

Attachment:
1.png
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2 - Clear S.M.A.R.T. - Check S.M.A.R.T. - 3 sectors are there as relocated (as expected) :

Attachment:
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3 - Retrieve the first 100 LBA with DRE :

Attachment:
3.png
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Conclusion - Unless someone have a better idea - On my Quantum AS drive even adding sectors to G-List don't prevent access to them by LBA and will not replace them by spares.

WTF is going on here ????

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 4:48 
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Does anyone do this sort of research or are you all a bunch of pc3k addicted data recovery wanna be guys ?
I do understand that long time data recovery pros aren't going to share anything, but it's a little bit sad that people entering the data recovery field now and buying tools and experimenting NOW aren't even bother to comment any of my testings/experiments/findings, while i bet many are taking advantage of what i share to make money out of fixing drives...
I'm tempted to start publishing my research on modern drives on the "secret" section of my forum and provide access only to members who share and take part on this sort of experiments from now on.
Regards.

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 5:29 
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I would like to help you and do some test too, i have a Quantum drive but i can't do any test with it because MRT doesn't support it.
Also my old PC3000 PCI doesn't support Quantum drive. :?


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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 5:46 
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michael chiklis wrote:
I would like to help you and do some test too, i have a Quantum drive but i can't do any test with it because MRT doesn't support it.
Also my old PC3000 PCI doesn't support Quantum drive. :?


Hi !
No problem.
I do understand that.
Thanks for posting.

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 6:18 
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michael chiklis wrote:
I would like to help you and do some test too, i have a Quantum drive but i can't do any test with it because MRT doesn't support it.
Also my old PC3000 PCI doesn't support Quantum drive. :?


Not wanting to be rude, the read/write long and read/write commands are standard ATA commands, you could use mhdd or the free demo of sht if you want an ATA terminal for windows to do the experiment !

The new generation of data recovery people, like you, are too attached to what the comercial tools do and people don't research and don't understand the basic concepts of how the drives work any longer.

If MRTLab/pc3k/sd whatever tool don't support the drive then it's over.

That was my point.

This experiment started with standar ATA commands only, no requirments were made to use VSC.

Hddl is another free ATA terminal...

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 6:27 
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I attached my Quantum Fireball drive (very very old) to computer, i can't do anything with it because is not detect anymore in the BIOS.
It does head knocking noises, but sometimes gets detected in bios and works fine (it is detect in bios 1 time every 30/40 power-on cycle) :?

I think i need tools because i can't tell which is the problem (heads, bad surface, PCB, firmware) ??
Seem that pc3000 ISA supports quantum drives, but i don't have it :(


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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 6:28 
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Does the following help explain it?

Code:
Sectors are considered to contain grown defects if the 14/15/16 10-bit symbols ECC
algorithm must be applied to recover the data. If this algorithm is successful, the
corrected data is stored in the newly allocated sector. If the algorithm is not
successful, a pending defect will be added to the defect list. Any subsequent read to
the original logical block will return an error if the read is not successful. A host
command to over-write the location will result in 4 write/read/verifies of the
suspect location. If any of the 4 write/read/verifies fail, the new data will be written
to a spare sector, and the original location will be added to the permanent defect
list. If all 4 write/read/verifies pass, data will be written to the location, and the
pending defect will be removed from the list.


http://www.seagate.com/staticfiles/maxt ... Manual.pdf


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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 7:08 
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michael chiklis wrote:
I attached my Quantum Fireball drive (very very old) to computer, i can't do anything with it because is not detect anymore in the BIOS.
It does head knocking noises, but sometimes gets detected in bios and works fine (it is detect in bios 1 time every 30/40 power-on cycle) :?

I think i need tools because i can't tell which is the problem (heads, bad surface, PCB, firmware) ??
Seem that pc3000 ISA supports quantum drives, but i don't have it :(


Probably dying heads.
At any rate thanks for trying it out.

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 7:15 
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Cris wrote:
Does the following help explain it?

Code:
Sectors are considered to contain grown defects if the 14/15/16 10-bit symbols ECC
algorithm must be applied to recover the data. If this algorithm is successful, the
corrected data is stored in the newly allocated sector. If the algorithm is not
successful, a pending defect will be added to the defect list. Any subsequent read to
the original logical block will return an error if the read is not successful. A host
command to over-write the location will result in 4 write/read/verifies of the
suspect location. If any of the 4 write/read/verifies fail, the new data will be written
to a spare sector, and the original location will be added to the permanent defect
list. If all 4 write/read/verifies pass, data will be written to the location, and the
pending defect will be removed from the list.


http://www.seagate.com/staticfiles/maxt ... Manual.pdf


Thanks.
That would explain, for example, a modern wd royl that places the pending sector on the re-lo list and the swapped sector on the g-list.
On the old quantum there are only G-list and P-list, and if i add by hand a sector to G-list on S.M.A.R.T. Is just counted as relocated, yet it's not swapped by a spare.
So for the sector to be swapped for a spare what should i do ? Would it go to P-list instead ?

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 8:00 
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That text I quoted was from a "Quantum Fireball Plus AS 10.2/20.5/30.0/40.0/60.0 GB AT Product Manual".

My understanding from the text I quoted is that there can be an entry in the grown defects list, without there being a reallocated sector.

If the sector had an error and it had to (and could) be recovered by the "14/15/16 10-bit symbols ECC algorithm", it creates a reallocated sector, and puts the ECC corrected data into the reallocated sector. {Perhaps this automatically skips the G-List and puts an entry in the P-List}

If the sector had an error and it could NOT be recovered by ECC, the drive adds the sector to the grown defects list, but does NOT create a reallocated sector. However, if you later try and write to this sector in the grown defect lists, and it fails, it will then create a reallocated sector.

So perhaps for this drive, the G-List is really only a "pending sectors list", and SMART just counts the entries in the G-List for the reallocated sector count, even if not technically correct.

Code:
So for the sector to be swapped for a spare what should i do ?


I guess you would have to do a write long, with just enough corruption in the "user data" for the "14/15/16 10-bit symbols ECC algorithm" to repair the data.

Or maybe try write long with incorrect ECC data twice.


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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 8:13 
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Ok, thanks !

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 15:38 
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Cris wrote:
That text I quoted was from a "Quantum Fireball Plus AS 10.2/20.5/30.0/40.0/60.0 GB AT Product Manual".

My understanding from the text I quoted is that there can be an entry in the grown defects list, without there being a reallocated sector.

Thanks for the explanation. The same question was bugging me, too. I managed to reproduce the same problem on my own drive.

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 Post subject: Re: Need Help Understanding Quantum AS BAD SECTORS - G-list
PostPosted: March 25th, 2015, 15:48 
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Spildit wrote:
Does anyone do this sort of research or are you all a bunch of pc3k addicted data recovery wanna be guys ?

My observation is that the vast majority of "professionals" are just point-and-click users who are able to regurgitate standard solutions but fall over as soon as they encounter an unfamiliar problem. How many times have you seen the response "no solution from Ace lab yet"?

Spildit wrote:
I do understand that long time data recovery pros aren't going to share anything, ...

No, I don't understand that at all. Quantum drives are extinct.

Spildit wrote:
... but it's a little bit sad that people entering the data recovery field now and buying tools and experimenting NOW aren't even bother to comment any of my testings/experiments/findings, while i bet many are taking advantage of what i share to make money out of fixing drives...

How do you help the DIY-ers without helping the leeches as well?

Spildit wrote:
I'm tempted to start publishing my research on modern drives on the "secret" section of my forum and provide access only to members who share and take part on this sort of experiments from now on.

That's what they want.

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