Hard drive sometimes found - sometimes not

My backup drive is a 500GB WD and has experienced no issues at all until I deleted one partition and resized the remaining one with (Partition Wizard 8). I thought it a bit odd when PW reported a 31MB unallocated space remaining, but on reboot the BIOS detected the drive and in Windows all the files on the resized partition were present.

A subsequent reboot and the drive is not found again. Nothing has physically changed inside the case. Any ideas on might be going on?

Hello RogerR!

To see if I have understood, you know that the drive occasionally disappears because it sometimes doesn't show up in BIOS?
When it does, what does it show, also as mode? Is it possible to show a screen shot of Disk Management to see the partitions left and format?
Also, has anything unusual or sudden occurred, like a power surge or disconnected cable or anything of the sort?

CK_WD

I know the drive disappears because it is not present in explorer, disk manager, or anywhere else. When present it appears as a Basic Disk. No unusual power events, in fact no issues at all with the system until I deleted the second partition. It's the backup drive and backups had been performing to that disk normally until now.

It is an IDE drive and appears as a slave.

That means that it doesn't show up in Disk Management also? Please, if you manage to make it seen, post a screenshot from Disk Management! Whe you see the basic drive, is it written as Unallocated or RAW?

It looks like by deleting that partition you've damaged the partition table somehow. My advice would be to move your backups from the drive to another location, then fully write zeros to the drive and reformat it.

For the drive to show up in the system, first check the cables, if one hasn't by any chance burnt out or something else, then check the settings of the drive in BIOS. Change it if you have to to AHCI.

Also, how many other drives plugged in do you have?

CK_WD

Note the 31MB unallocated despite the full size of the disk appearing as the G: drive.

Yes, it does seem like reformatting the disk is the option, PITA though it is.

Yes, it is quite unpleasant, but the drive is given as healthy, has a drive letter so physically it should be fine.
The partitions just have encountered a problem; could be the partition's table, unsuccessfully resizing after deleting the other partition and etc.
The safest way is just to move your back ups where you have free space, write zeros fully, repartition and reformat the drive in NTFS and the problem should be cleared.

Best of luck! :)

CK_WD

Follow-up question here CKWD;

The two WD drives (5000AADS and 5000AACS) are unjumpered and connected via SATA cables to separate SATA channels, but always appear as Master and Slave on Channel3. I presume this is a legacy of operating in Native IDE mode? I don't remember any more why I set it up that way, but I do have a recollection that switching to AHCI mode is a no-no if it was not that way when installing the OS.

Does this have bearing on the issue?

Well, this would depend on your OS.
In the past the problems with changing IDE mode to AHCI were bluescreens that could only be fixed with either changing back the setting in BIOS or reinstalling the OS. This happened due to only the IDE storage driver being configured in Windows. At the same time the AHCI driver is missing, thus Windows can't read from the hard drive and gives out a BSOD with error code 0x0000005B.
But if you have Windows Vista or newer, you could first change the registry keys, thus enabling the AHCI driver in Windows before the changes in BIOS.
But now enabling AHCI is better, gives out better performance than IDE.

CK_WD

I'm using W7 Ultimate and I boot from a SSD. I tried adopting AHCI (editing the msahci key in Regedit) but just got a lengthy boot time (as the BIOS detected the drives) and a hang at DMI pool data. Perhaps my 790X chipset is too old (2009) to see the benefits?

I did over-write the backup drive and reformat and it seems largely to be working normally. I do have an odd 8MB unallocated block at the start of that disk which I can't seem to do anything about, but 8megs off 465gigs isn't exactly crippling, so I am living with it.