I have upgraded to win 7 64-bit from xp. With xp I had my WD 15 EARS Green drive set-up with the jumpers set to 7 and 8. With win 7 the drive is performing painfully slowly, and I have read that this may be due to the jumper being on 7&8–a setting that is recommended only for XP. The drive takes ages to perform the most basic tasks, and when I have multiple tasks on the go then it freezes up for minutes. So I removed the jumper and rebooted to find that the boot manager is not found. Obviously this has messed with the partition because when I try a repair from the installation disk, no OS is seen. Will this require a reinstall of windows. I currently have 2 partitions on the drive, if I have to reformat and reinstall, will I need to do so for both, or only the partition with the OS? Cheers.
If you have the Windows installation disk, it will ask you in which partition you want to install the OS, but I’m not 100 % sure if it will format the entire drive.
In a nutshell, jumper 7-8 applies a +1 offset to the LBA number.
Windows XP creates partitions on track boundaries. This means that the boot sector of the first partition is at LBA 63. Since this is not a multiple of 8, this means that the partition would normally be misaligned. However, by applying a +1 offset to the LBA, the boot sector actually begins at LBA 64, not LBA 63, thus resulting in an aligned partition.
Windows 7, OTOH, creates aligned partitions by default. The first MBR partition begins at LBA 2048. If jumper 7-8 is installed, then the actual starting LBA becomes 2049, which misaligns the partition.
When you removed the jumper in the first instance, the Windows XP MBR became invisible because it was shifted by one sector. In fact if you use a disc editor (eg DMDE or HxD), you should find your original XP MBR at LBA 1.
In short, you will probably need to reinstall Windows. You could try WD’s alignment utility, but I suspect that it won’t be smart enough to understand what happened.
I tried upgrading my machine from XP to Win-7 x64 (machine is a Gateway GT5628 w/ an OEM’d Intel DG33BU mobo). With XP, I’d installed a WD15EARS as my boot media and performance and such were fine. I installed 8 GB of RAM and still worked fine. Went to install Win-7 x64 and would not install … would get almost to the end and say something like “A problem caused Windows 7 to not install properly” (no real data). Anyway, tried slipstreaming in tons of drivers and cleaning the disk of all data … no joy. Dropped in a WD740 and installed flawlessly … drop in the WD15 and fail … drop in the WD740 and worked fine … repeatable! Anyway, I then used Acronis to clone the drive from the WD740 to the WD15 and worked then fine. No idea why … but thought I’d share.