Data recovery: am I getting scammed?

[larry moe 'n curly]

No you didnt, because every surface has embedded servo info.

Thanks, Rod. was under the impression that only one of the platters
had a servo embedded into it because the hole for the servo writer
access seemed too small to let it access all the platters. So are you
saying that if a person was really careful and kept things clean, the
platters could be removed and put them back without doing any special
realignment, and the drive should still work OK?

 

[Eric Gisin]

The servo info is written identically by all heads during servo writing.

 

[Rod Speed]

Rod Speed wrote

Thanks, Rod. was under the impression that only one of the platters
had a servo embedded into it because the hole for the servo writer
access seemed too small to let it access all the platters.

The hole is for mechanical contact with the head assembly, not the platters.

So are you saying that if a person was really careful and kept things
clean, the platters could be removed and put them back without doing
any special realignment, and the drive should still work OK?

Normally not, essentially because with modern track spacings,
its going to be impossible to mount the platters concentric again.

The most thats normally done is to physically replace the head assembly instead.

 

[Arno Wagner]

Does each platter have an embedded servo? If not, how do they recover
the data from any platters that lack one but have been removed?

Yes. The servo "tracks" are today short servo bursts located between the
sectors.

Arno

 

[Arno Wagner]

By "servo platter" I mean the platter with the embedded servo in it.
If the platters of the bad drive are merely transplanted to another
drive to recover the data, what do they do to realign the platters that
lack any embedded servo?

Each data platter has its own servo information.

Arno

 

[Bob Willard]

I was under the impression that the embedded servo was recorded on only
one of the platters, and the other platters had to be aligned relative
to it. One reason I thought that was because the hole in the side of
the drive for writing the servo seemed too small to allow access to all
the platters.

As several of us have tried to explain, embedded servo means that the
servo info is embedded with the data -- on the same tracks.

 

[Folkert Rienstra]

Each data platter

Each track.

has its own servo information.

Arno

Can't even get the simple questions right.

 

[Alexander Grigoriev]

That hole is for laser interferometer, to control the heads position while
the servo if being written.

 

[Alexander Grigoriev]

The tolerance for the platter alignment is at the same order of magnitude as
the bearing's play (a few microns). It may not be possible to realign the
platter, since there are no visible marks on it. Keep in mind that the track
pitch is now about 1/10 micron.

 

[Arno Wagner]

Is there even still such a thing as embedded servo, i.e. special areas
on the surface which have servo info as opposed to data? It's not all
the same PRML data stream now?

The servos info is short, small ''bursts''. It does not take
much space, since it does not have to be read reliably or written.
Also the servo info is all over the platter, since a data track
is only readable if the heads are aligned pretty well on it.
But whereever the head is, it will find some servo track
it can read and that tells it where it is.

Arno

 

[Folkert Rienstra]

The servos info is short, small ''bursts''. It does not take much space,

since it does not have to be read reliably

No shit.

or written.

No shit.

Also the servo info is all over the platter,

No shit.

since a data track is only readable if the heads are aligned pretty well on it.

No shit.
And how exactly will it do that "pretty well" with servo data "that does not
have to be read reliably", babblebot.

But whereever the head is, it will find some servo track it can read and that
tells it where it is.

No shit.

Arno

Thanks for showing us your utter cluelessness once again, babblebot, as always.