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Only Recognizing 320GB of a 640GB HDD in BIOS and Win7

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January 20, 2010 11:25:34 PM

I just booted my new pc for the first time and noticed in the BIOS and in Windows 7 that only 320GB of a 640GB HDD is being recognized. This is my first pc build. So far so good. Now this 640GB HDD is from an older pc that I had. It is a good Western Digital drive. I believe it was partitioned to 320/320GB. I see it in the BIOS as just a 320GB drive and also in Windows. How do I get the system to recognize that other 320GB? I'm sure it is something simple I'm missing, I'm just not sure how to get it setup.

Also, I set my storage to AHCI instead of IDE. Is this ok? I've seen many suggestions to setup your hdd's this way. I just want to make sure I'm not screwing anything up.

I've successfully installed Windows 7 HomePremium (64bit) offline without any issues, so I'm doing something right. I'll probably run into some snags when I hook it up to the internet tomorrow. We'll see...

Any info would be apprecaited. Thanks so much!!!

BTW: I've got 2 500GB Samsung 7200rpm drives along with this WD 640GB drive in my system.

- manoolu
January 21, 2010 10:55:26 AM

Anyone have any ideas for me to recognize the other half of my 640GB hdd? Thanks!
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a c 346 G Storage
January 21, 2010 5:31:12 PM

Second question first re: AHCI. Yes, this is the right way to set the SATA port mode when you have Vista or Win 7 as your OS. The IDE Emulation mode was a convenient way around a problem between Win XP and SATA, and not necessary now. Moreover, using AHCI mode gets you all of the improved features of SATA whereas the IDE Emulation mode dropped some.

Now, how to find the missing Partition? I'm not clear on two questions: is this 640 GB drive your boot drive, or is it a second unit used for data? And, more important: is there data on the missing second Partition that you want, or can you afford to wipe it all out if necessary?

The tool to investigate this is Disk Management within Windows. Click on Start and in the menu RIGHT-CLICK on "My Computer"; in the mini-menu choose "Manage". In the resulting new window on the left expand "Storage" if necessary and click on "Disk Management". This shows you two panes on the right, each of them scrollable to see all their contents. The upper right one shows you all the drives Windows can use now, and it should have the Partition you can see now, your optical drive, and maybe your other (C: ) drive if there is one.

Now look at the LOWER RIGHT pane. It has a series of horizontal big blocks, each representing a hardware device in the system. For each large block there will be on the left end a small box with a label like "DISK_0", a size, and a couple more bits of info. To the right of that will be a group of sub-blocks, each representing one Partition on this drive unit. In some cases there may be only one large sub-block because the drive has only one Partition that occupies the entire space. There will be no real sub-blocks on your optical drive unit because you can't make separate Partitions on that device.

So, look first for the drive unit that holds your boot "drive" or Partition, and look at the info in the major sub-block. It should show you its letter name, "C:", a size, a File System like NTFS, and some other bits. Now, look for the large block that represents your 640 GB older drive unit. It should have one Partition that takes up roughly half of the disk's space with a letter name like "D:" or "E:", a size of about 310 GB, a volume name, a File System again like NTFS, etc. Next, look to the right of that and what does the next sub-block say? If it says "Unallocated Space", that is a chunk of disk real estate that has NOT been made into a usable Partition, and it can be used to make one. But if it shows you a File System (could be FAT32 or NTFS or RAW), what is that? Does it show a Volume Name? Important: does it have a letter name like"F:"?

One "glitch" that can happen is that Windows somehow fails to assign a letter name to a Partition that is perfectly good with a NTFS File System and everything, and then Windows can't access the Partition as a drive. IF that happens to be what you see, RIGHT-click on the block and choose Change Name from the mini-menu. Assign it any letter not in use. If this works, exit out of Disk Management and reboot your machine so the change gets into the Registry. If that goes OK, look in My computer to see if the missing Partition has shown up as a drive you can use.

Now, if the sub-block for the second Partition does not exist and it only shows one Partition and some Unallocated Space, one option is to simply use the Disk Management tools to Create a second Partition out of that space. BUT doing that certainly will destroy any old data sitting there, so if you think there's data you want do NOT do this. Instead you will need some utilities to recover a missing Partition and its data files.

If the sub-block is there but shows its File System as "RAW", this means there is trouble either with the Partition Table or with the File System installed in the Partition. Look around the web to get advice on Partition Recovery and file Recovery tools. And post exactly what Disk Management tells you here, so others can provide some of that advice.
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a c 346 G Storage
January 21, 2010 5:35:00 PM

OK, now I see from your second post that the equipment involves two new 500 GB Samsung drives, of which only one appears in My Computer, and this 640 GB older drive on which only one Partition is apparent.

First, I am guessing that the two Samsungs were new units and you installed your Operating System (Win 7) on one of them. What you probably did not realize is that the Install process did two important steps to prepare that one new drive for use, but that same preparation work has not been done yet for your second new drive. Let's deal with that first.

Disconnect power, open the case, and disconnect the power and data cables for the OLD (640 GB) drive to keep things simple. Close up, reconnect the power cord and boot up. See my earlier post on how to get into Disk Management and look at all the hardware devices in the LOWER RIGHT pane. You should be seeing one 500 GB drive with a C: drive partition on it, a second 500 GB drive unit with just Unallocated Space, and an optical drive unit. For the second 500 GB Samsung, RIGHT-click on its Unallocated Space and choose Create Primary Partition. You will have some choices to make in a Wizard that comes up to help. Set the type to be a Primary Partition, set its size to be the full size of the drive, and, assuming you will use this unit only for data, do NOT make it a bootable drive. For the File System to install choose NTFS unless you know you need FAT32 for something. You can choose between Quick Format and Full Format. Both will do the same initial job (in about 15 minutes) of creating a system for file management on the Partition. But the Full Format option then will continue on immediately to do a complete test of EVERY sector of the drive, and this will take MANY hours. On a new drive this is not necessary, but may be a useful precaution if you can leave the machine working on it for hours. On an older drive you are re-using I'd suggest this error-checking step is a good idea. When the job is finished back out of Disk Management and reboot the machine. You will now find a new Drive in My Computer ready to use.

Now, disconnect power and go back into the case to re-connect the old 640 GB drive unit. Close up, reconnect power and boot up. NOW is the time to use Disk Management as I described in my earlier post to investigate what its Partitions say. If you're really lucky they might BOTH look OK and have letter names already assigned. If that happens, just exit out of Disk Management and look in My Computer to see what is there ready to use. But if that not the case, make careful notes about what it does tell you about those Partitions on the 640 GB older unit and post them here for more advice.
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January 21, 2010 5:44:45 PM

Paperdoc said:
OK, now I see from your second post that the equipment involves two new 500 GB Samsung drives, of which only one appears in My Computer, and this 640 GB older drive on which only one Partition is apparent.


Thanks so much for all of that info! Good stuff. Now, I figured out the partition thing. I do see the entire 640GB now. Not sure what I did. I am still having difficulty with finding that second Samsung 500GB drive in Windows. Only one of them is showing up. I see it in the BIOS and it is named the exact same thing as the one that is being recognized. Now that I think of it when I clicked on 'devices and printers' in Win7 I saw two Samsung drives. But when I open 'My Computer' I am only seing one of them along with that other 640GB drive.

Sorry to be so vague, I'm trying to learn all of this stuff.

Thanks so much for your help! I know we can figure this out.

- manooly
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a c 346 G Storage
January 21, 2010 5:55:23 PM

We are both posting at the same time. See my second post for how to establish a Partition on the second 500 GB Samsung and Format it ready to use.

When you are done, check back here. With all this going on, the letters Windows has assigned to the drives may not be what you want. There is a simple way to set them to your liking, and doing that now before all kinds of files get installed is the right time. If you want to change them, tell us what drive letters you have, and what you wish they were, and we'll help.
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January 22, 2010 12:01:32 PM

I'm hoping to try your suggestions tonight after work. Thanks again! Stay tuned...
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!