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No access to WD passport disk.
Posted: 14 Aug 2015, 20:41
Hi I have an issue with a 500GB external disk.
When I plug-in it. My computer says that it recognizes the device, and it appears at Computer folder assigned to F: but I can't open it.
I downloaded testdisk and I'm running the analisys. Before it said that it had no type.
I know that originaly it had NFTS.
I wanna recover the device after getting the data out of the disk. But I'm compfortable if I only get the data.
Thank you in advance.
Re: No access to WD passport disk.
Posted: 15 Sep 2015, 11:53
This is my first post/reply in this forum.
I do not understand why the moderators (FIONA? ) do NOT insist that help requests be required to provide the make and model of the drive that is suspected of having an access problem, and requiring them to determine whether that drive is internal or external and MOST IMPORTANT whether the drive is a 512 byte native physical sector drive, or a.512 byte logical (512e emulated also known as an Advanced Format drive) with 4kb physical sectors, or a 4kb physical sector (4Kn native) drive (that is without on-drive 512 to 4096 byte translation).
I know that may seem like a lot of work, but GOOGLE is your friend.
Advanced Format is the new big thing in HDD manufacturing!
Originally 4K (4096 bytes) sectors was an engineering solution as a way to improve disk data recovery (normal every day). It also provided a convenient solution to overcoming the 2.2 TB limitation of the MBR partition table when using 512 byte physical sectors.
All of the initial discussion after the new 4K physical sector size was chozen then concerned how to make the drive compatible with most OSes and applications that were expecting to only work with 512 byte physical sector drives. Their compromized solution was the 512e Advanced Format drive that converts (on-disk) 512 byte write requests to 4096 byte writes instead. Many hdd mfrs & Microsoft do a good job explaing how the conversion works but they leave out that their example concers only a single 512 byte write to a 4K physical sector. Because all modern drives have hardware memory (buffers), the code actually waits a while before writing the buffer back to the disk, therein reducing the penalty of the READ, MODIFY,WRITE process that they describe.
All of this leads me to believe that Christophe should consider including the ability to determine from the drive itself whether it is 512byte logical/ 512byte physical (older drives), 4KB logical sector writes/4KBnative physical sectors, or 512byte logical sector writes/4096byte physical sectors.
Microsoft has Windows 8.1 (and by extension also Windows X - I mean 10).capable of using 4KBnative drives by having the conversion routines within Windows itself.
I would be remiss if I neglected to mention that now Western Digital is making ALL of its drives with 4KB sectors (they may save a disk platter on occasion). I know that 1 TB drives are for sure but suspect that 500GB drives are also. Sorry, I don't GOOGLE in the middle of a post.
Original Poster: do your homework first.
Christophe, please consider using the SATA commands at your disposal to discover the logical/physical relationship of drives as part of your process. I ruined a good ext AF drive's GPT structure before I realized I needed to change my geometry to 4096byte physical sectors!
That reminds me, on Windows systems (at least), drives larger than 2.2 TB cannot be partitioned using the whole drive without being set up as a GUID partition table (GPT) disk. That applies to Windows 7 which can only use a GPT disk as a secondary (ie DATA) drive.
Also a UEFI bios is required to boot a GPT drive.
Mr. Phelps, if any of your UEFI force are caught or mung-up your drives, we will disavow any knowledge gleaned here. This post will self-destruct after being read. Good Luck.