Jump to content

Why is my SSD randomly Disc 1 or 2, and how to fix it ?


Recommended Posts

Windows 7 64 bit


My discs are "normally" numbered :-

0 WDC WD64001AALS-00L3B2 (596.2 GB) GPT type HDD - not boot-able by my BIOS, Pagefile.sys + Utilities

1 Samsung HD103SJ (931.5 GB) MBR type HDD - Windows 7, Old system drive, now dormant, plus utilities.

2 OCZ-VERTEX2 (55.9 GB) MBR type SSD - Windows 7, Current system.


Standard AHCI 1.0 Serial ATA Controller (AHCI)

Channel 0, Target 0, Lun 0, Device: 0 : OCZ VERTEX2

Channel 1, Target 0, Lun 0, Device: 0 : WDC WD6401AALS-00L3B2

Channel 2, Target 0, Lun 0, Device: 0 : SAMSUNG HD103SJ

Channel 3, Target 0, Lun 0, Device: 0 : CD/DVD


Several times a month the OCZ is Disc 1 and Samsung is Disc 2.

The WDC is almost always Disc 0, but once it became Disc 2.


I am not aware of any major problems as a result of the numbers being wrong,

other than I use Hard Disk Sentinel to monitor the health of my discs,

and when I choose to show the SSD status in the notification tray then Windows only displays the state of whatever is Disc number 2.

I suspect and fear that other applications may suffer to a greater extent when Windows reports the wrong numbers.


When I designed computers I had all race hazards under control.

These Windows "features" irritate me.


I always shut down completely at the end of the day,

and IF I have no current work/files/windows in progress then also for a meal or T.V. break,

but mostly when something is in progress I choose to put Windows to SLEEP.


Whatever the Disc numbers were when I put Windows to SLEEP,

the numbers are always the same when I wake it up and log into Windows again WITHOUT seeing the BIOS activity screen.


The dice only seem to roll when I either do a total restart or I have shut down and then start up and the BIOS does its thing.


N.B. This random numbering was also an irritation when the BIOS had its activity screen disabled.


If I interrupt the BIOS to select a Boot Flash Drive

(either Macrium Reflect Rescue under WinPE or Minitool Partition Wizard under LINUX)

then even if I only use those tools to LOOK and not modify anything,

it is almost guaranteed that after removing the Flash Drive and exiting and letting the system automatically restart through a further BIOS startup,

then Samsung and OCZ will have swapped numbers.


I would appreciate :-

Information upon what determines the order in which these numbers are allocated ; and

any suggestions to stop this chaos.




Link to comment
Share on other sites

I believe the listing is based completely upon which port on the mobo they're in, and should not change unless you swap something (note: if you do this, drive letters will change as well)


I don't know why they would change around if you're not changing around the SATA ports

Link to comment
Share on other sites

  • Moderators

I don't know whether this will add any enlightenment Alan, but on a few occasions, after manually selecting the boot options screen to enable me to run a linux distro from a bootable flash drive, I've closed down the linux distro and then found that my computer won't boot.


The cause has been the same altering of the hard drive boot order in the BIOS. For example my non bootable internal hard drive has been placed ahead of the system drive, which resulted in nothing happening. Usually I get a black command line screen with a blinking cursor. Completely inactive cursor.


Why it happens I have no idea, but the first time it gave me a few butterflies. Now that I know what and why, it's easily put right, and I've simply put this down to windows foibles. But it's definitely caused by the booting linux flash drive, and it may just be down to one particular linux bootable flash drive installer.


I think I've used at least three or maybe four different installers, and it could be one of them or even all of them.


Maybe I'll test one day by installing the same linux distro to the same flash drive with each of the installers that I've used in turn, and see if it's down to one of them.

Link to comment
Share on other sites

No, I am not changing the ports.


My best guess is that although the HDD's take 5 seconds to spin-up before files can be accessed,

and the SSD is supposed to have no spin-up delay,

Perhaps the BIOS gets an instantaneous hardware status report from the WDC HDD,

and the Samsung is second in the race,

but the SSD firmware takes a few more mSec to conduct an inventory and remember what it is,

hence the SSD is third unless the Samsung stumbles at the starting gun.


My best guess fails however upon the first clean BIOS start-up following the use of a Boot Flash device.

Link to comment
Share on other sites

@Alan, this caught my eye:


1 Samsung HD103SJ (931.5 GB) MBR type HDD - Windows 7, Old system drive, now dormant, plus utilities.

2 OCZ-VERTEX2 (55.9 GB) MBR type SSD - Windows 7, Current system.


If you still have bootable info on your Samsung old system drive, it can cause problems. If you have not done so already, copy the important files from your old system drive, then format it to get rid of the bootable information & bootable flag. Then, move the data back to the drive.


Having 2 drives with bootable information can cause Windows to attempt to load the registry hive from one of the drives, & use it for the other drive. This will cause weird things such as part of your files on your normal bootable drive to appear to go missing as the references to them go missing because of Windows using the registry hive off the secondary drive.


I have found through experience, that having 2 bootable drives connected is NOT a fun thing to do, if you don't want to "lose" data. Running a recovery tool is less fun than knowing it could have been prevented.


Upon boot, Windows looks for the 1st bootable drive, & it is possible that the order may get switched around due to one or the drive initiating slightly faster or slower than usual. I am not certain this is your problem, but what happens if you do the suggestion above?

Link to comment
Share on other sites

The cause has been the same altering of the hard drive boot order in the BIOS. For example my non bootable internal hard drive has been placed ahead of the system drive, which resulted in nothing happening. Usually I get a black command line screen with a blinking cursor. Completely inactive cursor.

I have only used the Linux Boot Flash once and suffered this chaos.

I have often used the mini-Windows WinPE based Macrium Flash Drive and often suffer chaos.


I may have a cure for you :-

My system BIOS (American Megatrends version 2202.)

Under BIOS selecting BOOT menu and choosing the sub-menu "Hard Disc Drives",

I always see my three internal Drives from OCZ, SamSung, and WDC,

In that sub-menu I can choose any device and select from a sub-sub-menu one of three choices which are :-

To replace it from that position with either of the other two devices,

or to DISABLE it.

When I disable the WDC there is no complaint from Windows that it has lost Pagefile.sys,

and no change to speed of file access on files held on that drive.

The only discernible difference is that the WDC is no longer listed in the Boot Priority menu so it cannot ever boot (not that GPT can boot from my BIOS).

N.B. Even though it is "Disabled" and is excluded from the Boot Priority screen, it can still be selected in the Boot Selection Screen.


Perhaps your BIOS will allow you to similarly stop your non-Boot-able drive from gaining random priority.


I find that regardless of whether or not I have "disabled" the WDC drive, it is almost always Disc 0 :angry:

Link to comment
Share on other sites

@ Hazel

Thanks for the link, I will read and digest.

I hope that CNET do not stick me with a download manager :rolleyes:


@ Winapp2

I would rather be irritated by Windows than run the risk of blowing up my BIOS.

My personal Teamviewer Help Desk son lives 300 miles away - perhaps when he visits this might be an option.


@ Super Fast

It makes no difference when I remove the "Active" flag from the Samsung partition and remove the drive letter so Windows Explorer cannot see it.


Hard Disk Sentinel reports for both WDC and Samsung that

Drive Ready Time Typical 11 seconds


In practice I have observed that when I have made no use of the WDC for half an hour Windows will power it down.

From that state :-

If I point Windows Explorer at a partition on that drive, the W.E. "Address Bar" shows a progress bar for 5 seconds before it can show me files ;

If I double click a desktop short-cut to a file or *.BAT script on that drive, nothing seems to happen for 5 seconds until it has spun-up.


My SSD is not "Enterprise Grade", but I am pretty sure that its files will be accessible at least 4 seconds before the contents of either HDD.


N.B. I am aware that System Volume Information is a pig,

and Dual Boot XP and Vista/Windows 7 can have catastrophic effects on S.V.I. if the two partitions see one-another,

But I would have thought that once the system has decided which drive and partition to boot then Windows would be loaded and would load only the Registry Hives on this Boot partition.

Can Windows inspect all registry hives on all drives and take a random choice ?

Would it even do so if there is no drive letter for the partition I do not want to boot from ?

N.B. I have System Restore Disabled - It was not dependable under XP and Macrium Reflect meets all my needs and also obeys my commands.


I am certain that OCZ make very reliable SSD's that never go wrong for 99.99% of all customers.

Unfortunately it is the other 0.01% that start topics in the OCZ forums,

so it gives me peace of mind to know that if I am going to be in the special 0.01% group,

I can simply reboot (via Boot Selection Screen) into my Flash Drive Partition Wizard and set the active flag on the Samsung Windows Boot partition,

and then reboot via BBS into Samsung and I can instantly start posting.




Link to comment
Share on other sites

Windows, sadly, is not intelligent enough to discern that one bootable drive is more important than another. Any time that you have multiple bootable drives connected, you risk Windows corrupting the contents of one or more of the drives because of loading the registry hive for one bootable drive & utilizing it for another.


I had this happen to me a few times, before I realized what was going on & happened to actually catch the registry hive switching in action.

If this were me, & if I wanted to preserve a specific Disk 0 or Disk 1 lettering, as well as the Windows lettering for the drive... I would test a few of the following.


Different BIOS makers may react differing ways, but again, this is what I would do if this were me & I wanted to preserve it:


1) Determine which PATA/SATA cabling the BIOS reserved for Disk 0 & Disk 1. Determine my Disk 0/Disk 1 preference & connect to that cabling.

2) Disconnect all other internal drives, use only 1 drive at boot. Else, fully erase bootable info from the other drive, then re-add the files back that I use on it.

3) Experiment with Disk 0 & Disk 1 settings if necessary. It may be less likely to push a drive letter back if it is already back a letter, say Disk 1 as opposed to 0.

4) Experiment with bootable CD/DVD instead of flash drive media. See if it does the same.

5) Experiment with a BIOS update (if available) & if I am sure it is the correct one to use.


I am not 100% sure this will absolve your difficulties, but it may be worthwhile to try.

Link to comment
Share on other sites

Would Windows actually load a registry hive from the Samsung drive if the Windows partition was hidden by virtue of an absent drive letter ?


Please note that none of my 6 off partition letters ever change, only the physical drive numbers change.


My SSD is connected to "Channel 0" of the SATA controller.

I understand that when using the Windows Installation Disc it will naturally instal Windows to whatever drive is connected to channel 0,

and as a result the SSD on a different channel will not get the "benefit" of the Windows installation.

I therefore believe my SSD is using the optimum physical connection to the system.


Normally this problem appears perhaps once a week.

I am not prepared to disconnect the Samsung for a whole week to see if the problem is cured because the Samsung holds other pertitions I use each day.


During a "normal" month I make no Boot intervention with any Boot Flash or CD.

If that were my only concern then I would accept abnormal drive numbers for the 10 seconds it would take me to follow up with a hard restart.

The irritation is that several times a month without any provocation from myself the system will start up with the wrong drive numbers,

and the only consequences that I am aware of are :-


The horizontal bars which display the physical layout of partitions on each physical drive will be in the wrong sequence,

with the SSD in-between each of the HDD instead of below both

(though I really think it should be ABOVE both - but it is the chaotic instability that aggravates me most).

This is true of the displays on both Windows native Disc Management and the third party Minitool Partition Manager.


Hard Disk Sentinel which monitors the health of all drives continues to work well,

but Windows shuffles the the notification icons when Windows is allocating the wrong Drive numbers.






The problem remains when the Active Flag is removed from the Samsung drive in addition to removing any drive letter from the Windows partition.

I think that this should make it UN-boot-able.

Edited by Alan_B
Link to comment
Share on other sites

It would sound logical that removing the boot flag would keep Windows from doing this, but I I am not 100% sure that even this would stop it.


I have had the case that I had an internal primary OS HDD become corrupted when I also plugged in an external USB HDD with a bootable OS on the drive.

The thought I had was that while Windows was loading, I would plug in this drive & copy over data from it.


The nightmare that ensued caused me to have to run a data repair program because Windows grabbed the Registry Hive from one drive & used it for the other.

As I had no backup of the registry hive that got replaced, data recovery was what saved my butt.


Thus, I quickly learned never to plug in a drive while Windows was initializing, but always to wait till afterwards.

Link to comment
Share on other sites

Microsoft made fundamental errors in how they deal with SATA interfaces.




From the above, they identified the bug in the VISTA period and appear to admit :-

SATA 0 = DISK 0 - or possibly 1

SATA 1 = DISK 1 - or possibly 0

In my case a legacy code bug from VISTA is not fixed but complicated under Windows 7 thus :-

SATA 0 = DISK 2 - or possibly 1

SATA 2 = DISK 1 - or possibly 2


I wonder how much worse this bug is under Windows 8.


Incidentally, this bug impacted :-

Macrium Reflect in 2009, but they were issuing an update that year


In 2010 Paragoon Drive Backup were promising a suitable update.


Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.