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Disk numbering in Window 7

Community Veteran
Posts: 38,460
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Registered: 15-06-2007

Disk numbering in Window 7

I have no idea whether this is a Windows setting but looking at my disk drives using the Manage option there are three showing
Disk 1 which is the original one containing the master boot record and Win Vista boot
Disk 2 which was the next one added and has the Win 7 boot
Disk 0 which was the last one added and only has data at present
My question is why the latest one isn't Disk 2. Is it something in the bios
7 REPLIES
Superuser
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Re: Disk numbering in Window 7

Community Veteran
Posts: 38,460
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Registered: 15-06-2007

Re: Disk numbering in Window 7

Thanks - I think - as I don't fully understand it
However when I dismantle everything in a week or so when I replace the motherboard I will check which sata ports they are actually connected to
It would appear - from the bit I do understand - that it doesn't really matter as long as the boot order is set correctly in the bios although I suspect that even if it is wrong it will still finish up booting from the disk with the MBR
Community Veteran
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Re: Disk numbering in Window 7

My boot disk is disk 0 and my second disk is disk 1.  So an alternative question is why your computer started from one instead of zero.
Both my disks are bootable; I rely on the BIOS to set the boot order. 
sjptd
Grafter
Posts: 467
Registered: 01-09-2014

Re: Disk numbering in Window 7

As I read it, the article Maurice references basically says that the order depends on many factors and is unpredictable and may be inconsistent.  For example, different spin-up times may depend on the temperature of different disks at boot time and can change the disk order.
This should not affect boot as long as there is only one drive with an MBR: not sure what happens when there is more than one and they change order.
It should not affect Windows drive letter assignment, which is what matters in normal day-to-day running of the OS.  I'm not quite sure what Windows does to make the drive letters 'sticky' over reboot, but it seems to work.
The only thing to be careful of is when using programs such as parted that do use drive numbers.  Just make absolutely sure that you double-check the current drive order before doing anything that could be damaging.  I think most of us who dare use such programs are already pretty paranoid when doing so.
Moderator
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Re: Disk numbering in Window 7

My boot drive (c) SSD is on drive 2, drive 0 is another SSD and drives 1 3,4,5 contain the remaining internal drives.
External drive numbering does up to 17 according to Belarc.
What I have noticed is generally after I 'Eject' an external then power it down the next time I power it up it has the same drive letter even if lower drive letters are available due to other drives being off. But sometimes it is allocated a different letter. Never worked out how/why.

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nanotm
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Re: Disk numbering in Window 7

you can mnaully assign a drive letter in windows to each drive, it will then retain that letter no matter what else is connected, I fix my network drives at the end of the alphabet, reserved the middle for the multicard reader and kept the first portion for fixed and spare.
makes it easier then so I can always find the stuff I want in the same place (which also means the hyperlinks will point directly at the correct point) without needing to always check what letter was assigned this time...
as to the boot time and the numbering, that literally changes every boot, my drives will swap from 0>29 at random every day (that being the totally number of fixed "drives" in the case although most of them are just card reader slots) not that it matters very often and when it does I always use the disk part command suite
just because your paranoid doesn't mean they aren't out to get you
RobPN
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Re: Disk numbering in Window 7

Since my Windows95 days I've always given my Disks/Partitions a Volume Label which starts with the letter I've assigned to them, which can be useful especially when you need to identify them when, for example, you need to perform system repairs etc. outside of Windows when the letters assigned may not be the same as those in Windows.
It's usually easy to think of a word which can be descriptive of the drive or contents and then assign the first letter of the word as the drive letter; e.g  DCheesyownloads  F:Files  G:Games  M:Music  PTongueaging  etc.