Remove Secure Drive CDFS Partition from Transcend JetFlash USB Drive

Recently my friend bought a new USB Flash Drive (pendrive) – Transcend JetFlash 8GB JF 620.

This USB Flash Drive was different from other USB Flash Drives.
It had a CDFS partition.You might wondering how a USB Flash Drive can have CDFS partition.

CDFS partition on a USB Flash Drive

When a normal USB Flash Drive is plugged into a computer it shows up as a Removable Disk.In other words, you see a new drive in My Computer or Windows Explorer.
Removable Disk

When a USB Flash Drive containing a CDFS Partition is plugged into a computer it shows up as two drives.Removable Disk and CD.The CD drive appears as if the computer has another CD ROM drive with a CD inside it.
CD ROM Partition

This CD Drive which appears when the UFD is plugged in, is the CDFS partition.This behaves exactly like a CD ROM.You cannot delete files in the CDFS partition.This partition stays even if you format the USB Flash Drive.Only the Removable Disk partition gets formatted.

How can a USB Drive have a CDFS partition?

A USB Flash Drive contains a microcontroller and flash memory.The microcontroller implements the USB Mass Storage class.In a normal USB Flash Drive, the microcontroller is programmed to implement a Removable Disk.

In a USB Flash Drive with a CDFS partition,the microcontroller is programmed to implement a Removable Disk and a USB CDROM.

Remove or Modify the CDFS partition on Transcend JetFlash 8GB USB Flash Drive

To remove or modify the CDFS partition, the microcontroller inside the usb drive must be reprogrammed.

UPDATE:- Transcend has released a special tool to remove the CDFS partition. Download it here CD-ROM_Remover_v1.0.0.3.rar
Thanks to .iqqmuT for informing us about this special tool.This tool may work for those who are having problems with 32GB Transcend USB Flash Drives.

I had posted about JetFlash Online Recovery to repair your Transcend JetFlash USB Drives.

However, there is a special JetFlash Online Recovery Tool for this USB Drive.This special tool is only for JF620 USB Flash Drives.
I downloaded this tool.The zip file contained two files.

  • OnLineRecovery_620.exe
  • security_f.iso

Running OnLineRecovery_620.exe did not help.It did not remove the CDFS partition.However it made security_f.iso as the CDFS partition.This iso file is about 11mb and contains the securedrive.exe and related files.

To make your own CDFS partition you will have to replace security_f.iso with your own iso file.
I have tried not this.I also do not know whether bootable iso images will boot from the CDFS partition.

Since the above tool did not help me in removing the CDFS partition I searched for some Mass Production Tools.

I found a customized version of JetFlash Online Recovery Tool.

I downloaded this rar file and extracted it to get Alcor_Transcend_JetFlash_OnLineRecovery.exe.

I plugged in my friends’s JetFlash JF620 USB Flash Drive and executed Alcor_Transcend_JetFlash_OnLineRecovery.exe.

I followed the on Screen Instructions.After a few minutes the process was complete.I replugged in the USB Flash Drive and the CDFS partition was gone.
The size of the USB Drive also increased by about 11mb.Earlier this 11mb was occupied by the CDFS partition.



About the Author: Bharat Balegere

Bharat Balegere is a 27 year old blogger from Bengaluru. He is a technology enthusiast and loves tinkering with computers and usb drives.

16 Comments + Add Comment

  • Hi. I have transcend 16 GB jet flash model 620. I use Alcor_Transcend_JetFlash_OnLineRecovery.exe everyting is ok. CDFS partition has been removed. But i want CDFS partition again. How can i go back.
    Sorry my bad english.
    My best regards…

    • Download the tool from

      This contains a file called security_f.iso.This iso file will become the cdfs partition.

      • Hi. Thank you for answer. But when i try this program it says “No device detected”
        ChipGenius information that

        Device Name: +USB Yığın Depolama Aygıtı

        PnP Device ID: VID = 058F PID = 9380
        Serial Number: 5&&33AE2767&&0&&3
        Revision: (Information not returned)

        Device Type: Standard USB device –

        Chip Vendor: Alcor(??)
        Chip Part-Number: AU9380~9386

        Product Vendor: USB
        Product Model: Yığın Depolama Aygıtı

        Tools on Web:

        My best regards.

      • Could not find security_f.iso in online_recovery_2 need help.
        From your above link

        • After you expand the archive, you will get OnLineRecovery_JF620_v4.0.0.29.exe which is also an archive (self extracting and self running RAR) containing security_f.iso. You can extract it usng 7-Zip free archiver ( Although, OnLineRecovery tool should be able to find the needed .iso itself.

  • It not work on 32Gb JetFlash JF620 USB Flash Drive.

  • I contacted Transcend support and they gave this link:

    With this tool I was able to remove CDFS partition from 32Gb JetFlash JF620 USB Flash Drive.

    • Thanks .iqqmuT.
      I will update the article with this link.

  • I did try to replace security_f.iso with various other images and it does work. Boot-able images boot fine. But the emulation is not perfect. Very few computers are able to boot from both partitions (CDFS and plain). Most often one of them is not even visible in BIOS or boot menu. In the cases when CD image is boot-able, it cannot be used to boot Windows, neither installation media nor live CD. XP variants end up with BSOD reporting “unmountable_boot_volume”, and 7 flavoured complain at some stage that “A required CD/DVD drive device driver is missing”. Linux boots fine from virtual CD (tried Ubuntu and Slax), but Linux is easy to boot from any USB stick anyway. In my case, the CDFS partition has to go. The idea of pocketable DVD drive was attractive at the beginning, but in this case the implementation is incomplete (to be honest, it is pushed way beyond the original purpose of simple Windows-only DVD drive).

    • addendum:
      CDFS removed with CD-ROM_Remover_v1.0.0.3 can be restored with OnLineRecovery_620.exe.
      CD-ROM_Remover will not free the space occupied by CDFS, it will just make it invisible!

  • I just wanted to know if CDFS partition of transcend jetflash 620 usb drive can be used for auto-running of certain programs when plugged on to windows 7 system .
    Is their any way of editing this drive to get these results.
    I could have tried on my own but for that i am looking for these answer so that i could buy one after some senior help.

  • Thank you for this post. It’s very helpful. I have removed cdfs from jf620 successfully.

  • Thank you very much,my usb flash trancend 8gb is repaired

  • Another internet traveler here, giving thanks.

    I had a hard time figuring out why my brand new flash drive would not get recognized in my Xbox 360, when every other drive of mine worked. Turns out it was this CDFS nonsense at fault. I successfully removed it, and now it works fine. Thank you.

  • found a link to the tool here after finding its been removed from the main website

  • I Forget A User Name And Password My Jetflash 220 USB Drive.How Can Made It..?Plz Help Me.

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