Re: booting a clone from a Slave HD
- From: "Timothy Daniels" <TDaniels@xxxxxxxxxxxxx>
- Date: Fri, 11 Nov 2005 14:03:59 -0800
The operating system is not jumper-aware, and neither is it cable-position aware. All it knows is that what partition it was loaded from and that there are other partitions in the system associated with various HDs. To understand how an OS is selected and loaded, you have to know the boot sequence:
The BIOS checks the HD that is at the head of its HD boot order, and it passes control to that HD's Master Boot Record (MBR). The code in the MBR looks for the partition marked "active", and the MBR passes control to the Boot Sector in that partition. The boot sector finds the boot loader, ntldr, in that partition, and it passes control to that ntldr. ntldr reads the boot.ini file to see where the partition is that contains the OS - which may be the same partition or any other partition in the system (either primary or logical), or even a partition on another HD. In the language of boot.ini, "rdisk(0)" is the HD that is at the head of the HD boot order - i.e. "the HD at relative position 0" - and "partition(1)" means the 1st partition on the HD.
Obviously, which HD is at the head of the BIOS's HD boot order determines the path that the boot process takes, and only by *default* is that order determined by the Master/Slave settings. That default order is:
Master on IDE channel 0, Slave on IDE channel 0, Master on IDE channel 1, Slave on IDE channel 1, Master on IDE channel 2, Slave on IDE channel 2, etc.
If you remove the Master on IDE channel 0, the Slave on IDE channel 0 moves to the head of the HD boot order. Therefore, the Slave can contain the partition which starts the loading process.
But that is only the *default* order. At any startup, one can change the HD boot order in the BIOS, and that order will persist until the ROM's battery runs down. So *any* HD in the system can be put at the head of the HD boot order, and its MBR will direct control to its "active" partition, and the boot files in that partition will control the loading of the OS under the direction of its boot.ini file, and the boot.ini file can designate any partition in the entire system to be the source of the OS.
Getting back to the "vanilla" case, that in which an OS from a Master HD is copied to the Slave HD, all one has to do to make the Slave boot up the clone OS is to remove the Master HD. And one can do that by merely unplugging the Master HD, leaving the Slave still connected. When one re-connects the Master, it will again be at the head of the default HD boot order, and *it* will subsequently boot. To make the clone on the Slave be the booted OS, merely leave the Master disconnected, or reverse the jumpering, or go into the BIOS and reverse their positions in the HD boot order. Notice that if one uses jumpers (and not Cable Select) to designate Master vs. Slave, one can leave the previous Master at the end of the cable and jumpered as Slave, and leave the previous Slave at the mid-point of the cable and jumpered as Master. Master/Slave is only for the IDE controller to differentiate two HDs sharing the same cable, and beyond that, it's only to determine their relative *default* boot order.
In short, a Slave HD can contain the "System Partition", i.e. that partition that contains the ntldr/boot.ini/ntdetect.com files, and any HD in the system can contain the "Boot Partition", i.e. that partition that contains the OS. Ultimate control lies with the setting of the BIOS, not with whether a HD is jumpered Master or Slave or what its position on its cable is.
*TimDaniels*
"Richard Urban" wrote:
The operating system is drive and partition aware. If the original operating system was seen as the first partition on drive 0, the clone must be presented as the same when it boots. You do this by changing the drive cable and jumper positions.
Regards,
Richard Urban Microsoft MVP Windows Shell/User
"Timothy Daniels" wrote:Both points are untrue.
1) All that is necessary for the destination drive to boot is for the destination drive to at the head of the BIOS's hard drive boot order, and that the destination partition be marked "active".
To put the destination HD at the head of the HD boot order, enter the BIOS at startup time and manually change the boot order. Directions will be in the user's manual.
To mark the destination parition "active" (if there are more than one partition on the destination HD), use Disk Manager (rt-clk MyComputer/Manage/DiskManagement). Rt-clk the graphic of the destination partition and if "Mark Partition as Active" isn't grayed out, click on it.
2) One can *certainly* boot from a Slave HD. Master/Slave settings have no meaning at all to the boot loader. All that is necessary is that the booting HD be at the head of the BIOS's HD boot order. That can be done in either of two ways:
a) Enter the BIOS at startup time and manually put the the HD at the head of the HD boot order.
b) Remove the Master HD, and the Slave HD will automatically move to the head of the HD boot order.
No diddling with the jumpers is necessary in either case.
(MVPs: Please test these statement yourselves so as to stop propagating popular myths.)
Use the usual precautions when booting a WinNT/2K/XP clone for the 1st time:
Don't let the new clone OS see its "parent" when it starts up for the 1st time. The easiest way to do this is to remove the source HD before booting the clone. Thereafter, you can reconnect the HDs (jumpered however you wish) and the clone can be booted with the "parent" OS present - which will be seen by the clone as just another Local Disk having its own file structure, and files can be dragged 'n dropped between the tw HDs' file structures just as between partitions on the same HD.
If the clone OS is *not* on the HD at the head of the BIOS's HD boot order, it can still be started if the the boot.ini file on the booting HD is amended to "point" to the partition on the HD that does have the clone OS. IOW, you can implement multi-booting by amending the boot.ini file. But amending boot.ini and using WinXP's built-in boot manager to multi-boot is a topic for another thread.
*TimDaniels*
"Richard Urban" wrote:If you want to boot from the hard drive you just copied "to", you have to change the cables and jumpers on the drive so the drive is the primary master drive. You can not boot from the 2nd drive while it is connected as a slave unit.
--
Regards,
Richard Urban Microsoft MVP Windows Shell/User
.
- References:
- Re: MBR Problem? Help?
- From: Richard Urban
- booting a clone from a Slave HD
- From: Timothy Daniels
- Re: booting a clone from a Slave HD
- From: Richard Urban
- Re: MBR Problem? Help?
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