SCSI/SATA

  • Thread starter Thread starter Johnny
  • Start date Start date
J

Johnny

I have a question about a hard drive. Mine is going on five years old,
and I'm sure it won't last much longer.

In Device Manager, my hard drive is listed as SCSI, but I know it's an
SATA drive. I just wonder why it doesn't show up as an SATA?

The hard drive is a Hitachi hdp725025gla380

I'm going to replace it with a 500Gb 7200 RPM hard drive.

MY hard drive is a SATA 1.5, and I notice the new drives are SATA 3,
Will that be a problem?


Windows 7 Home Premium 32 Bit

Compaq

2.7 GH processor

2 GB RAM
 
Johnny said:
I have a question about a hard drive. Mine is going on five years old,
and I'm sure it won't last much longer.

In Device Manager, my hard drive is listed as SCSI, but I know it's an
SATA drive. I just wonder why it doesn't show up as an SATA?

The hard drive is a Hitachi hdp725025gla380

I'm going to replace it with a 500Gb 7200 RPM hard drive.

MY hard drive is a SATA 1.5, and I notice the new drives are SATA 3,
Will that be a problem?


Windows 7 Home Premium 32 Bit

Compaq

2.7 GH processor

2 GB RAM
Click to expand...

This has to do with the fact there was SCSI driver
support built into the Windows OSes. It makes it
easier for the hardware companies and their driver
writers, to write drivers. On some driver installations,
the installer even "runs twice", depositing one level
of the driver on each of the two passes. It's quite
comical to watch.

Windows
|
| SCSI storage path
|
SCSI Preprocessor (first level)
|
| CDB translated into actual command
|
Actual driver (second level)

The person writing the driver for your SATA drive,
"pretends" it is a SCSI drive, translates the
SCSI read or write command data block, into
something the SATA drive can use.

At one time, there was actually code in the SCSI Preprocessor
layer. There was an actual division of labor.

Now, on some of those installations, the SCSI Preprocessor
layer is nothing more than a label in Device Manager (fake layer).
And the lower driver is doing all of it. So no pretense in terms
of implementation.

Your experience might have happened, if there was some
Silicon Image separate chip for the SATA drive. If the SATA
drive was connected to the Southbridge, then the Windows 7
built-in IDE/AHCI/RAID drivers can take over, and the
word SCSI probably doesn't appear for those.

And the fun started, because there was an existing SCSI
stack, in even the old Windows OSes. And the hardware
people were even encouraged to use that route.
It wasn't an accident, but a convenient way to get the
job done. It could have meant, slightly less support
from Microsoft, to get driver writers to be successful.

*******

SATA III would be a problem on some older VIA and SIS chipsets.
There used to be a tech note from Seagate on the matter.

Try page 11 here.

http://www.seagate.com/staticfiles/...uides/dm_11_sata300_installation_guide_en.pdf

One poster claims the VIA 6421A is "fixed". And my VIA 8237S
worked OK with a SATA II drive. Otherwise, with
a SATA III drive, it only jumpers down to SATA II,
rather than SATA I. And then a SATA III drive would
not work, on one of the page 11 listed pieces of hardware.

You would need to learn more about your motherboard hardware,
to be able to predict success or not. The odds of
you arranging the right stuff to have a failure,
are pretty low. Lots of other hardware, will negotiate
down when required to do so. (I.e. Older SATA II or SATA I
motherboards, can work with SATA III drives. They're supposed
to negotiate a lower rate. And I don't know the flowchart
for that sequence, and how they decide to "gear down".)

HTH,
Paul
 
This has to do with the fact there was SCSI driver
support built into the Windows OSes. It makes it
easier for the hardware companies and their driver
writers, to write drivers. On some driver installations,
the installer even "runs twice", depositing one level
of the driver on each of the two passes. It's quite
comical to watch.

Windows
|
| SCSI storage path
|
SCSI Preprocessor (first level)
|
| CDB translated into actual command
|
Actual driver (second level)

The person writing the driver for your SATA drive,
"pretends" it is a SCSI drive, translates the
SCSI read or write command data block, into
something the SATA drive can use.

At one time, there was actually code in the SCSI Preprocessor
layer. There was an actual division of labor.

Now, on some of those installations, the SCSI Preprocessor
layer is nothing more than a label in Device Manager (fake layer).
And the lower driver is doing all of it. So no pretense in terms
of implementation.

Your experience might have happened, if there was some
Silicon Image separate chip for the SATA drive. If the SATA
drive was connected to the Southbridge, then the Windows 7
built-in IDE/AHCI/RAID drivers can take over, and the
word SCSI probably doesn't appear for those.

And the fun started, because there was an existing SCSI
stack, in even the old Windows OSes. And the hardware
people were even encouraged to use that route.
It wasn't an accident, but a convenient way to get the
job done. It could have meant, slightly less support
from Microsoft, to get driver writers to be successful.

*******

SATA III would be a problem on some older VIA and SIS chipsets.
There used to be a tech note from Seagate on the matter.

Try page 11 here.

http://www.seagate.com/staticfiles/...uides/dm_11_sata300_installation_guide_en.pdf


One poster claims the VIA 6421A is "fixed". And my VIA 8237S
worked OK with a SATA II drive. Otherwise, with
a SATA III drive, it only jumpers down to SATA II,
rather than SATA I. And then a SATA III drive would
not work, on one of the page 11 listed pieces of hardware.

You would need to learn more about your motherboard hardware,
to be able to predict success or not. The odds of
you arranging the right stuff to have a failure,
are pretty low. Lots of other hardware, will negotiate
down when required to do so. (I.e. Older SATA II or SATA I
motherboards, can work with SATA III drives. They're supposed
to negotiate a lower rate. And I don't know the flowchart
for that sequence, and how they decide to "gear down".)

HTH,
Paul
Click to expand...


Thanks for taking the time to explain that. It's very interesting.

I took your advice and learned more about the motherboard, and it looks
like I have a SATA 3 hard drive. I don't know why I thought it was a 1.5.

I don't think there will be a problem. See if you agree.

Manufacturer: ASUS
Form factor: Micro-ATX- 24.4 cm (9.6 inches) x 24.4 cm (9.6 inches)
Chipset: NVIDIA GeForce 6150SE nForce 430

Hard drive
Size: 250 GB
Interface: SATA
Transfer rating: 3.0 Gb/sec
Rotational Speed: 7200 RPM
 
Johnny said:
Thanks for taking the time to explain that. It's very interesting.

I took your advice and learned more about the motherboard, and it looks
like I have a SATA 3 hard drive. I don't know why I thought it was a 1.5.

I don't think there will be a problem. See if you agree.

Manufacturer: ASUS
Form factor: Micro-ATX- 24.4 cm (9.6 inches) x 24.4 cm (9.6 inches)
Chipset: NVIDIA GeForce 6150SE nForce 430

Hard drive
Size: 250 GB
Interface: SATA
Transfer rating: 3.0 Gb/sec
Rotational Speed: 7200 RPM
Click to expand...

3.0Gb/sec is SATA II.

And theory says you should not have a problem connecting
a SATA III drive to your SATA II port. It should run
at SATA II rates.

http://en.wikipedia.org/wiki/Serial_ATA

SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
SATA revision 2.0 - 3.0 Gbit/s - 300 MB/s
SATA revision 3.0 - 6.0 Gbit/s - 600 MB/s

The cable encoding, sends ten bits, and upon receipt
eight bits are forwarded. That's an 8B10B code, and
results in the factor of 10 conversion between bits
and bytes. (Bits on the cable versus
bytes of actual thruput.) Cable coding schemes
exist to make design of receiving hardware easier.
8B10B might have originally been used on AC coupled
fiber optic receivers.

Paul
 
3.0Gb/sec is SATA II.

And theory says you should not have a problem connecting
a SATA III drive to your SATA II port. It should run
at SATA II rates.

http://en.wikipedia.org/wiki/Serial_ATA

SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
SATA revision 2.0 - 3.0 Gbit/s - 300 MB/s
SATA revision 3.0 - 6.0 Gbit/s - 600 MB/s

The cable encoding, sends ten bits, and upon receipt
eight bits are forwarded. That's an 8B10B code, and
results in the factor of 10 conversion between bits
and bytes. (Bits on the cable versus
bytes of actual thruput.) Cable coding schemes
exist to make design of receiving hardware easier.
8B10B might have originally been used on AC coupled
fiber optic receivers.

Paul
Click to expand...

I guess I was confused by the revision numbers and the bits per second.

I have looked at 500 GB Seagate and Western Digital hard drives, and
both are less than a hundred dollars.

I have to say this Hitachi hard drive has been a good one, and may last
many more years, so I'm just going to unplug it and leave it in the
computer.

I heard the life of a hard drive is about five years, and I don't want
to be sitting here one day when it crashes, and have to wait for a hard
drive to be delivered.
 
Have you considered mirrored raid?
Click to expand...

I looked it up.

"RAID I, for example, writes two copies of the data simultaneously on
two separate drives. This is called fault tolerant because if one of the
mirrored drives suffers a mechanical failure (e.g. spindle failure) or
does not respond, the remaining drive will continue to function."


I don't think I need to do that. I don't have anything real important
on my computer. I'm fine with just unplugging the old hard drive and
having it for a back up.

I could see where it would be necessary in an industrial control situation.
 
I looked it up.

"RAID I, for example, writes two copies of the data simultaneously on
two separate drives. This is called fault tolerant because if one of the
mirrored drives suffers a mechanical failure (e.g. spindle failure) or
does not respond, the remaining drive will continue to function."


I don't think I need to do that. I don't have anything real important
on my computer. I'm fine with just unplugging the old hard drive and
having it for a back up.

I could see where it would be necessary in an industrial control situation.
Click to expand...

I'm running some old array that is mirrored and striped. That is raid10.
Not suggested these days. But mirror raid is pretty simple. Just a
thought. Raid still doesn't mean you shouldn't back up, but it makes it
very unlikely you will lose data. I'm not sure how old this array is.
When were 300G drives state of the art? ;-)

I rebuilt the array once. Nothing lost, though the rebuilding process is
a bit creepy. You delete the bad disk from the array and then the BIOS
rebuilds it. Since I was running in what they called a degraded state (I
presume that means no data loss but no redundancy either), I backed up
the array first and then did the rebuild. It took forever.

In your case, you can just clone the drive weekly to an external USB. I
got a 500G external usb for $40 at Frys for SSD cloning.

Mirror raid makes reading the data faster for magnetic memory. Writes
take the same time.
 
3.0Gb/sec is SATA II.

And theory says you should not have a problem connecting
a SATA III drive to your SATA II port. It should run
at SATA II rates.

http://en.wikipedia.org/wiki/Serial_ATA

SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
SATA revision 2.0 - 3.0 Gbit/s - 300 MB/s
SATA revision 3.0 - 6.0 Gbit/s - 600 MB/s

The cable encoding, sends ten bits, and upon receipt
eight bits are forwarded. That's an 8B10B code, and
results in the factor of 10 conversion between bits
and bytes. (Bits on the cable versus
bytes of actual thruput.) Cable coding schemes
exist to make design of receiving hardware easier.
8B10B might have originally been used on AC coupled
fiber optic receivers.

Paul
Click to expand...

The new hard drive is installed, and I didn't have any problems, and
didn't need any jumpers.

I have to say one thing about Western Digital drives, they are tough.

While taking the drive out of the bubble wrap, I dropped it on a
hardwood floor, and there was no damage.

I ran a diagnostic scan and found no problems. Windows 7 is working fine.

I installed Vista first before installing Windows 7, and it activated
automatically.
 
Johnny said:
I have to say one thing about Western Digital drives, they are tough.

I dropped it on a hardwood floor, and there was no damage.
Click to expand...

Ouch!

Drives are a lot better on shock than they used to be. At one
time, the allowed shock while a drive was running, was only 2G.
The head assembly and arm now, is a lot stiffer, and that provides
a bit better protection.

The definition of "G's of shock" is a bit weird. If you drop
the hard drive a distance of two inches, onto a heavy steel plate
with a flat surface, it would be ruined for sure. That's because
the steel plate brings the drive to a stop almost instantly (instant deceleration).
In the physics lab, when we dropped a steel ball onto a steel plate,
the lab equipment said the peak force was 1000G. And that exceeds
the 300G limit on some hard drives. So when two unforgiving materials
meet, the peak G force is quite high.

The more "give" the floor has, the lower the G forces (for two drives
dropped from the same height). If the floor was carpeted, the G forces
would be relatively low. The carpet has a lot of give. Hardwood flooring
has some give to it, and isn't nearly
as stiff as a steel plate. The hard drive probably would have
been damaged, if it was running (spinning) at the time you
dropped it. The "running" G limit is lower than the "parked" G limit.

When the drive is not being used, the head slides up a landing ramp.
That provides clearance between the heads and the platter, and is
one of the reasons your dropped drive did no damage. A "head crash",
if the drive is spinning, leaves a ding mark in the platter surface,
and that area will have bad sectors afterwards.

There are a couple pictures in this PDF, of the landing ramp. Hitachi
is the former IBM hard drive division, and they were a great source
of information about hard drive design (i.e. how it works).

http://www.hgst.com/tech/techlib.ns...5825FB/$file/LoadUnload_white_paper_FINAL.pdf

When you send a hard drive for warranty repair, the terms of the warranty
say your claim can be rejected if too many G's of force were applied.
The wording of the warranty implies they have a "shock watch" inside the
HDA. That's a device that changes color, if dropped onto a hard surface.
So while you may have dodged a bullet today, it's always possible at
some future date, you ship in that drive, and they reject it based
on what the simple mechanical recorder of shock says. It's just a
"threshold" device, and all it says is "I detected more than 300G
of force". Something along those lines. They can also reject
a warranty claim, if the HDA housing is marked up (obvious hammer
marks :-) ).

Good luck,
Paul
 
Back
Top