HDD Regenerator - any good?

[Thomas]

Is HDD Regenerator any good?

At http://www.abstradrome.com/ it says it has the:

ability to detect physical bad sectors on a hard disk drive surface
ability to recover physical bad sectors (magnetic errors)



But it also says:

HDD Regenerator will not change the logical structure of the hard
disk drive.

Is it any good?

 

[eric]

On Sat, 14 Aug 2004 09:31:01 +0100, Thomas <call_me@115_015.com>
wrote:

I have used this program with decent results. I was working on a hd
with problems and used this program and it found bad sectors and
"repaired" them. Sunsequently it was able to load an OS, something it
was not able to do before without errors.

The debate about this program is whether it really "reapirs" or just
hides. Personally, I don't care. All scans now show this HD to be free
of errors.

To my mind it's a ;little like giving chicken soup to a dying man: it
can't hurt.

e.

 

[J. Clarke]

Is HDD Regenerator any good?

At http://www.abstradrome.com/ it says it has the:

ability to detect physical bad sectors on a hard disk drive surface
ability to recover physical bad sectors (magnetic errors)



But it also says:

HDD Regenerator will not change the logical structure of the hard
disk drive.

Is it any good?

It appears to try to read the data off a bad sector and rewrite it--when it
does that the sparing mechanism present on all modern drives maps out the
bad sector and maps in a spare and so your disk appears error-free.

The right solution to an increasing number of bad sectors on a drive is to
replace the drive while most of the data is still intact, not dink around
with utilities that merely delay the inevitable.

 

[Arno Wagner]

Thomas wrote:

It appears to try to read the data off a bad sector and rewrite it--when it
does that the sparing mechanism present on all modern drives maps out the
bad sector and maps in a spare and so your disk appears error-free.

You can have that cheaper: Just run a complete surface scan. Usually
the free diagnostics utility from the manufacturer can do that.
Or do a long self-test with a SMART tool. BTW, on some (most?) disks
reading 'weak' sector successfully already triggers the reallocation
mechanism, at least from my observations.

The right solution to an increasing number of bad sectors on a drive is to
replace the drive while most of the data is still intact, not dink around
with utilities that merely delay the inevitable.

If they keep increasing, definitely the only sensible approach.

I had had some cases recently where 100 or so reallocated
sectors showed up in the SMART log, but in a single event and
no further ones despite of two weeks of permanent complete surface
scans (I tried to drive the SMART values into the 'fail' area).

I guess such singular events could be external influences, like
temporaty vibration, temporary power problems or the like.

Arno

 

[Folkert Rienstra]

You can have that cheaper:

Not for that "try to read the data off a (physical) bad sector" part.

Just run a complete surface scan.

That doesn't work for unrecoverable read error bad sectors.
A surface scan doesn't attempt to read a sector with anymore vigour than
a normal read does. All it will do is report a bad sector and mark it.

Usually the free diagnostics utility from the manufacturer can do that.

It is not interested in your data, only on reporting bad sectors and
giving you an opportunity to get rid of them by overwriting your data.

Or do a long self-test with a SMART tool.

That will only mark bad sector candidates.

BTW, on some (most?) disks

All recent ones.

reading 'weak' sector successfully already triggers the reallocation
mechanism, at least from my observations.

Right, which obviously you don't need that program for.

When that doesn't happen and the standard retry count by drivers doesn't get
the data, that is when you need a special program that keeps trying until it gets
it errorfree by using some strategies not already used by the Error Recovery
Procedures of the drive itself. Or will interprete continuously differing read
results and combine those results to reconstruct the data to the most likely
pre-failure content and write that back to the damaged sector address.

You also need a special program to get rid of sectors that successfully read
after retries but that don't trigger the sparing process.

If they keep increasing, definitely the only sensible approach.

The only sensible approach is to find out what is causing the drive to
behave like that.

I had had some cases recently where 100 or so reallocated
sectors showed up in the SMART log, but in a single event and
no further ones despite of two weeks of permanent complete surface
scans (I tried to drive the SMART values into the 'fail' area).

I guess such singular events could be external influences, like
temporaty vibration, temporary power problems or the like.

Right, so you actually know that replacing it mindlessly without
checking probable causes is a stupid thing to do.

 

[Folkert Rienstra]

Is HDD Regenerator any good?

At http://www.abstradrome.com/ it says it has the:

ability to detect physical bad sectors on a hard disk drive surface

Well, that is obviously wrong unless is sprouts a small microscope on the
drive's heads to inspect the surfaces. ;-)
But it is possible to predict whether a sector is physically bad (defect)when seperate reads with ECC error result in reading
different data every
time as opposed to exactly the same data each time (written defect).

ability to recover physical bad sectors (magnetic errors)

Actually, magnetic errors do *not* constitute physical bad sectors:
"A media defect is physical damage to the recording capability of the media
while magnetic damage is a defect in the bit pattern written to the media.
"
There is no way to recover original data from a written defect
other than by interpretation and/or correction by the user.

But it also says:

HDD Regenerator will not change the logical structure of the hard
disk drive.

Which likely means that it only works with drives that have the bad sector
sparing mechanism and has no idea about logical structures (file systems).
Spinrite does a similar job but it knows about FATs and can even copy a
cluster with a bad sector to a different free cluster on drives that don't spare sectors and adjust the FATs and directories
accordingly.

Is it any good?

Maybe. Depends on what you expect from it/want to use it for.
For me, the webpage doesn't inspire much confidence.

 

[Joep]

You also need a special program to get rid of sectors that successfully read
after retries but that don't trigger the sparing process.

But 'normally' this would trigger the sparing process? And under what
condition wouldn't it?

 

[Arno Wagner]

But 'normally' this would trigger the sparing process? And under what
condition wouldn't it?

And also disregarding that there is a pretty large distance
between a failed read and a completely successful read
that did not need the ECC. Most sucessful retries with initial
failure will actually only work because of the ECC and trigger
reallocation. Unless it was an external event, like vibration,
that caused the initial failure. In this case there is no need
to reallocate.

I think not everybody in this thread understands what ECC is...

Arno

 

[Folkert Rienstra]

But 'normally' this would trigger the sparing process?

You appear to have snipped the "this". Presumably you meant:

reading 'weak' sector successfully already triggers the reallocation
mechanism, at least from my observations

If the sector is read with retries after a specific ERP/DRP point is reached.

God knows what he meant with "at least from my observations" when
that cannot possibly be 'observed'.

And under what condition wouldn't it?

If the sector is read with retries but that specific ERP/DRP point is not yet reached.
There can be up to 50 steps in a recovery procedure.

ERP = Error Recovery Procedure. DRP = Data Recovery Procedure
The data recovery process is a set of measures outside of normal operation
that is invoked to get the drive to read a sector when normal operation fails.

Here are a few terms as used in the DRP process of my IBM DFHS.

Reread - Read with no parameters altered.
Rewrite - Write with no parameters altered.
Read Bias - 0 = Normal Bias Current in Read Head,
+ 1 = Increase Bias Current in Read Head by 1 unit,
-1 = Reduce Bias Current in Read Head by 1 unit.
TO - Track Offset movement of the Read Head slightly off center. The percent
indicates the fraction of a track width. The sign indicates the direction of the
movement with + being toward the inner diameter of the data surface.
ECC Burst - Amount of ECC correction applied. Double Burst will correct a
41 bit error and under certain conditions can correct up to a 48 bit error.
These are errors per physical sector.
DA - Double burst ECC correction on adjacent error bytes.
DR - Double burst ECC correction on adjacent or random
TB - Triple burst ECC correction on adjacent error bytes. This allows 9 bytes
in error to be corrected.
SAT - Surface Analysis Test ECC correction on adjacent error bytes. This
allows certain 14 byte errors to be corrected when a thermal asperity is involved.
EQ - Equalizer Adjust, the Channel Hardware is set to a fixed mode with the
equalizer adjusted based on the amount shown.
TA Mode - Set the channel to thermal asperity recovery mode regardless of
whether a thermal asperity was detected or not.
NSF - No Sector Found error.
NO ID Mode - Data recovery using tangentially adjacent sector IDs to deter-
mine the physical location of the NSF ID. A physical operation is performed to
read or write the data.
HSC - Head State Change, A short write is done in the non-customer data area
to change the residual head state characteristics.
VCO Calibrate - Calibrates the Voltage Controlled Oscillator in the Channel
Hardware.
A/D Calibrate - Calibrates the Anolog to Digital Convertor in the Channel
Hardware.
Scrub - Movement of the head in an attempt to recovery from an error possibly
caused by a Thermal Asperity. Scrub is done in a particular direction, either
toward the Inner Diameter(ID) or toward the Outer Diameter(OD). Asperity
off the disk. Several disk revolutions are taken on each step which employs this
type of recovery.
Read Gate Adjust Recovery - Adjust where Data Sync is read in an attempt to
avoid a Thermal Asperity in the Data Sync Field. The amount of adjust is
fixed. The polarity of the adjust can be early or late.

 

[Joep]

You appear to have snipped the "this". Presumably you meant:

Yes, I did, sorry ...

If the sector is read with retries after a specific ERP/DRP point is reached.

God knows what he meant with "at least from my observations" when
that cannot possibly be 'observed'.


If the sector is read with retries but that specific ERP/DRP point is not yet reached.
There can be up to 50 steps in a recovery procedure.

ERP = Error Recovery Procedure. DRP = Data Recovery Procedure
The data recovery process is a set of measures outside of normal operation
that is invoked to get the drive to read a sector when normal operation fails.

Here are a few terms as used in the DRP process of my IBM DFHS.

Reread - Read with no parameters altered.
Rewrite - Write with no parameters altered.
Read Bias - 0 = Normal Bias Current in Read Head,
+ 1 = Increase Bias Current in Read Head by 1 unit,
-1 = Reduce Bias Current in Read Head by 1 unit.
TO - Track Offset movement of the Read Head slightly off center. The percent
indicates the fraction of a track width. The sign indicates the direction of the
movement with + being toward the inner diameter of the data surface.
ECC Burst - Amount of ECC correction applied. Double Burst will correct a
41 bit error and under certain conditions can correct up to a 48 bit error.
These are errors per physical sector.
DA - Double burst ECC correction on adjacent error bytes.
DR - Double burst ECC correction on adjacent or random
TB - Triple burst ECC correction on adjacent error bytes. This allows 9 bytes
in error to be corrected.
SAT - Surface Analysis Test ECC correction on adjacent error bytes. This
allows certain 14 byte errors to be corrected when a thermal asperity is involved.
EQ - Equalizer Adjust, the Channel Hardware is set to a fixed mode with the
equalizer adjusted based on the amount shown.
TA Mode - Set the channel to thermal asperity recovery mode regardless of
whether a thermal asperity was detected or not.
NSF - No Sector Found error.
NO ID Mode - Data recovery using tangentially adjacent sector IDs to deter-
mine the physical location of the NSF ID. A physical operation is performed to
read or write the data.
HSC - Head State Change, A short write is done in the non-customer data area
to change the residual head state characteristics.
VCO Calibrate - Calibrates the Voltage Controlled Oscillator in the Channel
Hardware.
A/D Calibrate - Calibrates the Anolog to Digital Convertor in the Channel
Hardware.
Scrub - Movement of the head in an attempt to recovery from an error possibly
caused by a Thermal Asperity. Scrub is done in a particular direction, either
toward the Inner Diameter(ID) or toward the Outer Diameter(OD). Asperity
off the disk. Several disk revolutions are taken on each step which employs this
type of recovery.
Read Gate Adjust Recovery - Adjust where Data Sync is read in an attempt to
avoid a Thermal Asperity in the Data Sync Field. The amount of adjust is
fixed. The polarity of the adjust can be early or late.

Thanks Folkert!