Sunday, April 5, 2015

T100TA 32GB Recovery Partition Notes

some users might have to send their T100TA to ASUS for repair. when they get it back, they find out that their SSD has a new 8GB recovery partition on it, and wasnt there before. the 32GB T100TA actually contains a hidden 8GB recovery drive embedded inside of the unit, and is only unhidden when a user performs a system refresh or reset. on a 64GB T100TA, the recovery partition is on the SSD itself and as such, this variant doesnt have an embedded recovery drive like the 32GB version. there have been 2 confirmed users who have received their units back from ASUS restored back to the original, proper way; myself being one of them.


how to unhide this partition:

  1. bring up the charms bar, open Search and type in Recovery 
  2. select Recovery Options 
  3. underneath the Refresh section, click "Get started" 
  4. as soon as the banner with "Preparing" appears, press cancel right away 
  5. close this and enter Disk Managment (diskmgmt.msc) 
  6. you should see a new Disk that is 7.04GB in capacity with a Read Only attribute 


how to assign this partition a drive letter:

  1. open an elevated Command Prompt window 
  2. type diskpart, press enter 
  3. type list disk 
  4. you should see the recovery drive, make note of the disk number 
  5. type sel disk #, where # is the disk number of the recovery drive 
  6. type assign letter=?, where ? is an unused drive letter 
  7. type exit, press enter 


* when you restart the system, the drive will lose its assigned drive letter and will become hidden again


how to view and copy the contents of this drive:

  1. in file explorer, go to view > options 
  2. click on the View tab 
  3. select the option "Show hidden files, folders, and drives" 
  4. uncheck the option "Hide protected operating system files (Recommended)" 
  5. browse to the recovery drive 
  6. you should be able to see the contents now. copy everything to another disk for safe keeping just in case. 

when i figure out how to create a recovery USB using the contents from the hidden recovery drive, i will post here.


the partitioning of the SSD is as follows, according to Disk Management:


100MB (EFI) - 700MB (Recovery Partition) - 28.21GB (Primary Partition)


the second partition is just the Windows Recovery Environment and doesnt necessarily contain a recovery image. i personally believe that this partition, when created by the factory restore image, or from ASUS themselves, actually points to the recovery image located on the hidden recovery drive. it accesses it by volume ID, and not a drive letter. my reasoning for this theory is because when you use a recovery drive created from within windows, it repartitions your drive, losing the ability to press F9 on boot to enter recovery mode (via ASUS factory image).


make note that when you create a recovery drive from within windows and use it to do a system recovery instead, it will copy over the contents of the hidden recovery drive to the SSD, losing 8GB of space. also, you cannot use F9 to recover anymore.


i also want to bust the myth around here that you can only use the embedded recovery a few times. as long as you dont screw around with the SSD partitioning you should be fine to use it as many times as you want.


if you want to make absolute sure that you arent going to get screwed out of 8GB from your ASUS RMA, or if you are playing around with the SSD and its partition layout, save yourself the headache and just make a complete disk image and store it somewhere safe. that way, if you get it back from ASUS with the recovery partition copied to the SSD, you can just restore the SSD with the image you made earlier, preserving the partitioning layout and the F9 to recover function.


Enabling write access on hidden recovery drive


ddscentral, a user on the transformerbook forums, has found a way to enable write access to the hidden recovery drive for those of you who want to explore the possibility of creating your own restore images:

Originally Posted by ddscentral

Sorry for bump, just wanted to share.

For those who have the 32GB version with a read-only recovery ROM:
To access it, open Task Scheduler, disable "AC Reminder" task and reboot.

The recovery ROM is just guts of a standard 8 GB (really 7.5GB) USB flash drive soldered to the motherboard.
I've managed to unlock and reformat the recovery drive using a low-level format utility from flash controller manufacturer Phison, called Phison Format & Restore.

The drive is not very fast (27.5 MB/s read, 4.5 MB/s write), but it does provide extra 7.5 GB of disk space in addition to 32 GB primary drive.

Originally Posted by ddscentral
You can download the format utility from this site:


Here's how I did it:

First, mount the drive
1. Run diskpart
2. Type: list volume
3. Find a volume called "Restore", note it's index. Then type: select volume
4. Type: assign letter=H: (or any other unused drive letter)
A new drive should appear.
Exit diskpart.
Now run the format utility as administrator (either from command line or make a shortcut)
Restore-v3.13.0.0.exe H:\
First, click the Restore button.
When restore completes, click Format.
In the window that opens, select "USB DISK 2.0" and click the Format button.
The drive should now be formatted and writable.