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Trying to understand SATA drive listing


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#1 grindy

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Posted 27 September 2010 - 04:21 PM

Hi all,

I have a 2 year old Dell system that has a single SATA HD and a single SATA DVD drive. My question is this: The HD shows up in setup as Drive 0 (so far so good), but it is also listed as "3rd Master". Could someone please tell me why the only HD in the system would be listed as "3rd Master" ? (System works fine, just trying to understand SATA technology here). :thumbsup:

Thx

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#2 hamluis

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Posted 27 September 2010 - 05:06 PM

The motherboard numbers each SATA slot on it.

If the board has 4 slots, the motherboard manual will show them in a diagram, with numbers 1, 2, 3, and 4.

This normally has nothing to do with booting, since any bootable drive can work from either slot. Example...on this board, I have 4 SATA slots, with 1 empty, 2 occupied, 3 empty, 4 occupies. My boot partition/Windows install is on the drive in slot 2.

Within the BIOS, the boot order determines which slot is tried...and in what order.

As long as I have the drive in slot 2 as the first bootable hard drive...and as the first boot option...it all works as it should.

I guess that Dell uses the term "master" to as a carryover from the days of PATA drives, where it was deemed (by some) necessary for a drive to be at the Master end of the cable to be bootable.

Of course, there are no "slave" drives with SATA.

Louis

#3 Platypus

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Posted 27 September 2010 - 08:07 PM

I think hamluis is on the right track.

The first (or only) hard drive becomes Drive 0, this is standard convention.

Being 3rd Master is I think related to legacy IDE compatability, as suggested. Enhanced IDE (EIDE) will normally have 2 IDE ports, each with Master & Slave. The Master location on the first IDE port address is Primary Master, on the second it's the Secondary Master. If a third port address exists, it's the Tertiary Master. These could equally be called 1st Master, 2nd and 3rd.

If the motherboard has an IDE port or ports, any IDE drive fitted to them would be 1st or 2nd Master. Even if there are no physical IDE slots, the SATA interface can be set to IDE emulation mode, in which case the drive would probably occupy the first IDE port address as the Primary Master, and be called 1st Master. Even though SATA does not have Master & Slave functions, the BIOS may identify SATA channels as Master/Slave to indicate how each drive will be designated in IDE emulation mode. If your BIOS leaves 1st & 2nd Master slots free for possible future IDE drives, the SATA drive becomes 3rd Master.

Edited by Platypus, 27 September 2010 - 08:18 PM.

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#4 grindy

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Posted 28 September 2010 - 04:35 PM

The motherboard numbers each SATA slot on it.

If the board has 4 slots, the motherboard manual will show them in a diagram, with numbers 1, 2, 3, and 4.

This normally has nothing to do with booting, since any bootable drive can work from either slot. Example...on this board, I have 4 SATA slots, with 1 empty, 2 occupied, 3 empty, 4 occupies. My boot partition/Windows install is on the drive in slot 2.

Within the BIOS, the boot order determines which slot is tried...and in what order.

As long as I have the drive in slot 2 as the first bootable hard drive...and as the first boot option...it all works as it should.

I guess that Dell uses the term "master" to as a carryover from the days of PATA drives, where it was deemed (by some) necessary for a drive to be at the Master end of the cable to be bootable.

Of course, there are no "slave" drives with SATA.

Louis


Thanks Louis and Platypus for your responses... :thumbsup:

The system board does have SATA slots 1-4 and the drive was using slot 1. I disconnected the SATA DVD (just so its "numbering" couldn't effect anything) and connected the HD to SATA 2 to see what it would say. When I did this (and the HD now the ONLY drive in the system) it reported that it was now the 4th Master. It still works fine, but I'm still just as perplexed as ever as to Dell's "numbering" system.

Bob :flowers:

#5 DaChew

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Posted 28 September 2010 - 08:34 PM

What model dell?

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No. Try not. Do... or do not. There is no try.

#6 Platypus

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Posted 28 September 2010 - 08:41 PM

When I did this (and the HD now the ONLY drive in the system) it reported that it was now the 4th Master. It still works fine, but I'm still just as perplexed as ever as to Dell's "numbering" system.

I suspect that's probably due to the ESCD (Extended System Configuration Data) held in the CMOS memory. The BIOS maintains an equipment list using ESCD, and would still have a record of the drive on the first port being allocated 3rd Master, so it designates a drive it finds on the next port 4th Master. SATA drives are hot-swappable, so as far as the BIOS knows, the 3rd Master could be in a hot-swap bay and you might plug a drive back into it at any time. That's my guess anyway.

If you cleared the CMOS memory, or went into the BIOS setup and used a possible option "Clear ESCD", the drive numbering would possibly change.

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#7 grindy

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Posted 30 September 2010 - 11:12 PM

When I did this (and the HD now the ONLY drive in the system) it reported that it was now the 4th Master. It still works fine, but I'm still just as perplexed as ever as to Dell's "numbering" system.

I suspect that's probably due to the ESCD (Extended System Configuration Data) held in the CMOS memory. The BIOS maintains an equipment list using ESCD, and would still have a record of the drive on the first port being allocated 3rd Master, so it designates a drive it finds on the next port 4th Master. SATA drives are hot-swappable, so as far as the BIOS knows, the 3rd Master could be in a hot-swap bay and you might plug a drive back into it at any time. That's my guess anyway.

If you cleared the CMOS memory, or went into the BIOS setup and used a possible option "Clear ESCD", the drive numbering would possibly change.


I appreciate your input, but it doesn't explain why the BIOS reports the ONLY drive in the system as the 3rd Master.

#8 Platypus

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Posted 01 October 2010 - 08:06 AM

We're surmising it's because the 1st and 2nd positions are being held for IDE drives. The standard device allocation for EIDE allows two Master and two Slave drives. This reference shows them included among all the standard device resource allocations made by the BIOS:

http://www.pcguide.com/ref/mbsys/res/config_Summary.htm

"The entries in bold represent the default resource usage in a typical PC; entries in regular text are optional resource allocations, or resources used by optional or non-standard devices"

Presented in a different form:

http://www.pcguide.com/ref/mbsys/res/ioSummary-c.html

At port address 1F0-1FFh the Primary IDE controller, master drive - at address 170-17Fh the Secondary IDE controller, master drive. So to the BIOS, these two IDE drives' standard locations would be 1st Master, 2nd Master.

Even if they do not currently attach to a drive, a drive using another interface, eg the SATA controller on the motherboard, will not be located at either of those addresses but will have a third address, so it will be logical for the BIOS to classify it as 3rd Master.

As I said in post #3:

"If your BIOS leaves 1st & 2nd Master slots free for possible future IDE drives, the SATA drive becomes 3rd Master."

Edited by Platypus, 01 October 2010 - 08:08 AM.

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