Which drive mode (LBA or Normal) for a laptop HDD?

[Knack]

Will be attempting a data recovery from an IBM Travelstar 2.5" laptop HDD
that was manufactured in 2002. Autodetection of this HDD from a regular PC
gave 3 options to choose from; one was LBA ,mode and the other two were
Normal mode. Only one of the options gave the correct number of heads for
this HDD, and that was one of the Normal mode options, so I'm leaning toward
setting up the drive for Normal mode. However, all of the other drive
parameters will have to be edited. I'm wondering whether I should select LBA
mode and edit *all* of the parameters instead.

1) What mode is a laptop HDD normally setup for, LBA or Normal? (the BIOS
setup in this HP pavilion xf255 laptop provides no such info; only date,
time, and boot device)

2) Is there any risk of me corrupting this drive if I attempt to extract the
data using an improper mode setup in BIOS for it?

 

[Rod Speed]

Will be attempting a data recovery from an IBM Travelstar 2.5"
laptop HDD that was manufactured in 2002. Autodetection of
this HDD from a regular PC gave 3 options to choose from;
one was LBA ,mode and the other two were Normal mode.

You should be setting AUTO as the drive type in the bios.

Only one of the options gave the correct number of heads
for this HDD, and that was one of the Normal mode options,
so I'm leaning toward setting up the drive for Normal mode.

Nope, that wont work with a Win OS.

However, all of the other drive parameters will have
to be edited. I'm wondering whether I should select
LBA mode and edit *all* of the parameters instead.

You should be setting the drive type to AUTO instead.

1) What mode is a laptop HDD normally setup for, LBA or Normal?
LBA

(the BIOS setup in this HP pavilion xf255 laptop
provides no such info; only date, time, and boot device)

2) Is there any risk of me corrupting this drive if I attempt to
extract the data using an improper mode setup in BIOS for it?

Yes, if you use different geometry details than what
were used when the drive was used previously, and
you write to the drive, you can bugger it up completely.

 

[Knack]

You should be setting AUTO as the drive type in the bios.


Nope, that wont work with a Win OS.


You should be setting the drive type to AUTO instead.



Yes, if you use different geometry details than what
were used when the drive was used previously, and
you write to the drive, you can bugger it up completely.

From my reading at http://www.pcguide.com/ref/hdd/geom/geom.htm I just now
realized that the values labeled on the exterior of the HDD must *all* be
given as LBA, since the the number of heads is given there as 16 (that can
only be a nominal LBA value). The manufacturer, IBM, wouldn't mix Normal and
LBA values on the same label.

I'm using AUTOdetection, but the LBA parameters that autodetection lists are
incorrect! At the very least, it should get the number of LBA heads right.
But the number of LBA cylinders also don't match either. So if I choose the
autodetected LBA mode, then I'll still have to edit most if not all of the
LBA drive parameters in the Standard CMOS Setup screen of the BIOS setup
utility.

Does the BIOS write an overlay on the HDD even if you just want to read from
it; not format it? If the HDD was originally setup in a laptop in LBA mode,
and I keep it in LBA mode for data recovery via another PC, wil I mess up
this HDD by editing the autodetected drive parameters, since they don't
match the parameters labeled on the HDD's exterior? Do LBA parameters ever
match the parameters listed on the HDD's label?

 

[Arno Wagner]

Will be attempting a data recovery from an IBM Travelstar 2.5" laptop HDD
that was manufactured in 2002. Autodetection of this HDD from a regular PC
gave 3 options to choose from; one was LBA ,mode and the other two were
Normal mode. Only one of the options gave the correct number of heads for
this HDD, and that was one of the Normal mode options, so I'm leaning toward
setting up the drive for Normal mode. However, all of the other drive
parameters will have to be edited. I'm wondering whether I should select LBA
mode and edit *all* of the parameters instead.

1) What mode is a laptop HDD normally setup for, LBA or Normal? (the BIOS
setup in this HP pavilion xf255 laptop provides no such info; only date,
time, and boot device)

Depends. Newer systems ofteh use LBA.

2) Is there any risk of me corrupting this drive if I attempt to
extract the data using an improper mode setup in BIOS for it?

Depends _very_ much on the tools/OS used. If you use Linux,
1) the disk geometry of the BIOS will not matter since Linux
looks at the info on disk only 2) you can do any mounting as
read-only and prevent any writes to that disk.

If the data is valuable, I strongly suggest you get somebody
with experience with this type of task to assist you.

Arno

 

[Rod Speed]

From my reading at http://www.pcguide.com/ref/hdd/geom/geom.htm
I just now realized that the values labeled on the exterior of the HDD
must *all* be given as LBA, since the the number of heads is given
there as 16 (that can only be a nominal LBA value).

The manufacturer, IBM, wouldn't mix
Normal and LBA values on the same label.

You're massively confusing LBA with pseudo CHS values.

I'm using AUTOdetection,

I didnt say auto detection, I said the drive type should be set to AUTO.

but the LBA parameters that autodetection lists are incorrect!

There is no such animal as 'LBA parameters'. LBA uses the
logical block number and thats entirely separate from CHS values.

At the very least, it should get the number of LBA heads right.

There is no such animal as 'LBA heads'. LBA is an alternative to CHS.

But the number of LBA cylinders also don't match either.

There is no such animal as 'LBA cylinders' either.

The short story is that modern drives with pretend to have
the CHS values that appear in the bios drive type entry.

So if I choose the autodetected LBA mode,

You should be setting the drive type to AUTO.

then I'll still have to edit most if not
all of the LBA drive parameters

There is no such animal. There is JUST the maximum
logical block number that the drive supports.

And if you set the drive type to AUTO, the bios will
work all that crap out for itself and you wont even
see any CHS numbers in the drive type entry at all.

in the Standard CMOS Setup screen of the BIOS setup utility.

See above.

Does the BIOS write an overlay on the HDD

Nope, no bios ever writes and overlay. bios overlays can
be installed, but you dont want to do that in your situation.

even if you just want to read from it; not format it?

You dont want to load a bios overlay at all.

If the HDD was originally setup in a laptop in LBA mode,
and I keep it in LBA mode for data recovery via another
PC, wil I mess up this HDD by editing the autodetected
drive parameters, since they don't match the parameters

< labeled on the HDD's exterior?

Yes, if the drive was written using a drive type as
AUTO, you may not be able to see the data properly
if you play silly buggers with those CHS values.
You should be using an AUTO drive type instead.

The CHS values on the label are completely irrelevant
when you use the AUTO DRIVE TYPE ENTRY.

Do LBA parameters

No such animal. The ONLY LBA 'parameter' is the
maximum logical block number that the drive supports.

ever match the parameters listed on the HDD's label?

Nope, and if you use an AUTO drive type entry there arent
even any CHS values to compare with the label at all.

 

[Knack]

You're massively confusing LBA with pseudo CHS values.


I didnt say auto detection, I said the drive type should be set to AUTO.


There is no such animal as 'LBA parameters'. LBA uses the
logical block number and thats entirely separate from CHS values.


There is no such animal as 'LBA heads'. LBA is an alternative to CHS.


There is no such animal as 'LBA cylinders' either.

The short story is that modern drives with pretend to have
the CHS values that appear in the bios drive type entry.


You should be setting the drive type to AUTO.


There is no such animal. There is JUST the maximum
logical block number that the drive supports.

And if you set the drive type to AUTO, the bios will
work all that crap out for itself and you wont even
see any CHS numbers in the drive type entry at all.


See above.


Nope, no bios ever writes and overlay. bios overlays can
be installed, but you dont want to do that in your situation.


You dont want to load a bios overlay at all.

< labeled on the HDD's exterior?

Yes, if the drive was written using a drive type as
AUTO, you may not be able to see the data properly
if you play silly buggers with those CHS values.
You should be using an AUTO drive type instead.

The CHS values on the label are completely irrelevant
when you use the AUTO DRIVE TYPE ENTRY.


No such animal. The ONLY LBA 'parameter' is the
maximum logical block number that the drive supports.


Nope, and if you use an AUTO drive type entry there arent
even any CHS values to compare with the label at all.

OK. Thanks Rod. Following your advice I avoided autodection, went to the
Standard CMOS Setup display and simply set the mode to AUTO; not LBA; not
NORMAL; not LARGE.

The WinNT4(SP6a) computer sees the NTFS drive that came out of the WinXPH
laptop and data recovery is proceeding nicely so far. Many deleted files
have been found on the laptop's HDD, and are being restored to the HDD of
the other computer so as not to write over any of the remaining deleted
files. Thanks again

 

[Rod Speed]

OK. Thanks Rod. Following your advice I avoided autodection, went to the
Standard CMOS Setup display and simply set the mode to AUTO; not LBA; not
NORMAL; not LARGE.

The WinNT4(SP6a) computer sees the NTFS drive that came out
of the WinXPH laptop and data recovery is proceeding nicely so far.
Many deleted files have been found on the laptop's HDD, and are
being restored to the HDD of the other computer so as not to
write over any of the remaining deleted files. Thanks again

No problem, happy to help.

 

[Folkert Rienstra]

Nope, 16 is a typical PCHS value (see later).

Well, apparently you aren't alone.

Auto detection uses (L)CHS values, not (P)CHS.
It either reads the MBR or suggests a set of (L)CHS values.
Auto detection doesn't do anything for LBA addressing.

Yes, there is. They are the (L)CHS values used with 'LBA assist' mode.
( (L)CHS, logical CHS as used by the BIOS Int 13 call ).
( (P)CHS, Physical CHS as used by the IDE/ATA interface in CHS mode ).
Bios and IDE/ATA interface differ in extending the legacy CHS, that was
limited to 528MB 1024C/16H/63S, to 8GB by extending the number of
heads to 256 (Int 13) but still 1024 cylinders and extending the number
of cylinders to 65,536 but still 16 heads (ATA). Hence the use of tran-
slation from (L)CHS to (P)CHS (or LBA) and the term 'translating bios'.

Nope, LBA stands for LBA assist and calculates (P)CHS differently
from (L)CHS than Large mode does. 'LBA assist' _can_ translate (L)CHS
into an LBA and set the drive to LBA mode, but doesn't necessarily do so.

Nope, 'LBA assist' is an Int 13 CHS translation mode.
At a minimum a translation from (L)CHS into LBA.

Oh yes, there is. Just as there is LRG (Large) heads.

LBA is an alternative to CHS.

LBA addressing mode is, 'LBA assist' is a CHS translation mode that can
address all logical blocks where Large mode is a simpler translation
scheme, also known as Bit Shift mode, that can leave you with a partial
track or cylinder at the end of capacity that can't be addressed because
it isn't a full track (or cylinder).

There is.

Nope. That is utterly mangled.
IDE drives hold the default (P)CHS, not any (L)CHS.

(L)CHS is found in the MBR partition entries.

Which will come to the same conclusion as auto detect. It's AUTO
_mode_ that will make the decision on 'Large', 'LBA assist' or 'Normal'.

Nope. CHS translation setup is there for programs that use the
standard Int 13 interface. CHS translation setup is for programs
that use Logical CHS addressing and drives that either use Physical
CHS addressing (IDE) or LBA addressing (IDE and SCSI).

LBA addressing mode (Int 13 ext.) doesn't need any setup as there is no-
thing to setup, both programs and drives work using LBA addressing mode.

But they are still there for use with Int 13.

The CHS from the bios are pseudo LCHS that show the capacity
as if CHS would have extended beyond 8GB.
CHS however is limited to 8GB and that is what any drive lable of
any drive over 8GB will show. So punching them in will not change
any CHS parameters but because of the dual function in bios (set as
well as show) you may actually set the drive capacity fixed to 8GB.

And Mode type.

Never for Int 13. Only for LBA addressing mode (Int 13 ext.)

Sigh.

Pity the entry in Bios setup is in (pseudo) (L)CHS,
not LBA (Logical Block Address).

 

[Simon]

Nope, 16 is a typical PCHS value (see later).

Well, apparently you aren't alone.

Even you should be able to manage to do better
than that pathetic excuse for a troll, ****nert.

Auto detection uses (L)CHS values, not (P)CHS.
It either reads the MBR or suggests a set of (L)CHS values.
Auto detection doesn't do anything for LBA addressing.

Yes, there is.

Wrong. As always.

They are the (L)CHS values used with 'LBA assist' mode.

Those aint LBA parameters, fool. There is just ONE LBA
parameter, the maximum block number the drive supports.

( (L)CHS, logical CHS as used by the BIOS Int 13 call ).
( (P)CHS, Physical CHS as used by the IDE/ATA interface in CHS mode ).

None of that is LBA, fool. And the PCHS isnt used at
all with modern hard drives, for one very very simple
reason, the S varys in bands across the platters and
so PCHS isnt even meaningful with modern hard drives.

There is only ever LCHS where the drive can pretend
to be the CHS values listed in the drive type table.

Bios and IDE/ATA interface differ in extending the legacy CHS, that was
limited to 528MB 1024C/16H/63S, to 8GB by extending the number of
heads to 256 (Int 13) but still 1024 cylinders and extending the number
of cylinders to 65,536 but still 16 heads (ATA). Hence the use of tran-
slation from (L)CHS to (P)CHS (or LBA) and the term 'translating bios'.

Got sweet **** all to do with what is being discussed there,
whether there is more than one LBA parameter. There aint.

Yep.

LBA stands for LBA assist

Pigs arse it does. That term was used right back in
the >512MB drive days when LCHS ran out of capacity.

and calculates (P)CHS differently from (L)CHS than Large mode does.

Got sweet **** all to do with what LBA stands for.

You're massively confusing LBA with LBA
assist which is a different thing entirely.

'LBA assist' _can_ translate (L)CHS into an LBA and set
the drive to LBA mode, but doesn't necessarily do so.

PCHS cant even be used with modern hard drives
which dont have a constant S across the platters, fool.

Yep.

'LBA assist' is an Int 13 CHS translation mode.
Duh.

At a minimum a translation from (L)CHS into LBA.
Duh.

Oh yes, there is.

Drivel. There is JUST PCHS heads.

Just as there is LRG (Large) heads.

Still LCHS heads.

LBA addressing mode is, 'LBA assist' is a CHS translation mode
that can address all logical blocks where Large mode is a simpler
translation scheme, also known as Bit Shift mode, that can leave
you with a partial track or cylinder at the end of capacity that
can't be addressed because it isn't a full track (or cylinder).

Duh. And in practice only LBA is used to the drive.

The rest is just what the drive looks like to the OS etc.

There is.

Wrong. As always.

Yep.

That is utterly mangled.

Pathetic creature cant even manage its own lines.

IDE drives hold the default (P)CHS,

There can be no PCHS with modern drives where
the S varys in bands across the platter, fool.

not any (L)CHS.

Wrong again. The drive can pretend to have the CHS
values that are in the drive type entry. But that has size
limitations because of the range of CHS values allowed.

(L)CHS is found in the MBR partition entries.

And in the drive type table, when an AUTO drive type isnt used, fool.

Which will come to the same conclusion as auto detect.

How odd that it didnt.

Hope you have a large towel for that pathetic little face of yours, again.

It's AUTO _mode_ that will make the decision
on 'Large', 'LBA assist' or 'Normal'.

Wrong. As always.

Yep.

CHS translation setup is there for programs
that use the standard Int 13 interface.

That aint LBA, fool.

CHS translation setup is for programs that
use Logical CHS addressing and drives that
either use Physical CHS addressing (IDE)

Not even possible with drives that have the
S varying in bands across the platter, fool.

or LBA addressing (IDE and SCSI).

What I said, fool.

LBA addressing mode (Int 13 ext.) doesn't need any setup as there is no-
thing to setup, both programs and drives work using LBA addressing mode.
Duh.

But they are still there for use with Int 13.
Duh.

The CHS from the bios are pseudo LCHS that show the
capacity as if CHS would have extended beyond 8GB.

And they're never physical CHS values with modern hard
drives where the S varys in bands across the platter.

CHS however is limited to 8GB and that is what any drive lable of
any drive over 8GB will show. So punching them in will not change
any CHS parameters but because of the dual function in bios (set as
well as show) you may actually set the drive capacity fixed to 8GB.
Waffle.

And Mode type.

Most modern bios dont even have that anymore.

Never for Int 13. Only for LBA addressing mode (Int 13 ext.)

Wrong. As always. The numbers on the label are ALWAYS
completely irrelevant if you use an AUTO drive type entry.

Sigh.

Heavy breathing aint gunna save your bacon, trollchild.

Pity the entry in Bios setup is in (pseudo)
(L)CHS, not LBA (Logical Block Address).

Pity there aint any LCHS values at all in the
drive type table with an AUTO drive type entry.