Journalling Flash File System

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== Add USB Storage == == Add USB Storage ==
-* Routers with USB storage: A [[Linksys WRTSL54GS]] or [[ASUS WL-500g Premium]] device has USB capability (and more Flash and RAM).+* Routers with USB storage: A [[Linksys WRTSL54GS]] or [[ASUS WL-500g Premium]] device has USB capability (and more Flash and RAM). To enable USB on these devices see: [[USB_storage]]
** Some firmwares (older): Drivers and startup files are stored in a small amount of JFFS space ** Some firmwares (older): Drivers and startup files are stored in a small amount of JFFS space
-** Current firmware: USB support available within current v2.4 builds.+** Current firmware: USB support available within current v24 builds.
*Using 24SP1 Mega on an Asus WL-500W with external USB HDD: *Using 24SP1 Mega on an Asus WL-500W with external USB HDD:

Revision as of 10:13, 7 October 2008



Journalling Flash File System (JFFS/JFFS2) is a re-writable area within a DD-WRT-enabled device.

  • Located in /jffs.

Contents stored:

  • On DD-WRT Device main flash directly on the device (/jffs), or
  • mount --bind /storagelocation /jffs.
    Where storagelocation is
    • Off-board supplemental flash, see SD/MMC_mod, (/mmc/jffs).
    • Network Area Storage [NAS], or Server. (//servername/sharename)
    • JFFS reports as it's own free space, the free space on Share or SD Card, in the Web Interface

Examples of the kind of programs and data are:

  • Custom configuration files
  • NoCat splash pages and configuration
  • ipkg (Requires JFFS. See ipkg.)
  • Web-site hosting
  • Many other things.
  • JFFS must be Enabled for certain /jffs-dependent applications.

Enable JFFS: Create /jffs


On 4MB routers, enabling JFFS is made possible by using the DD-WRT Standard-NoKaid builds. NoKaid removes a specific XBOX module, leaving room for JFFS. The Mini builds of DD-WRT also work. This leaves between about 320KB - 700KB+ of available re-writable space in /jffs.

Very old versions of some Linksys routers (no longer manufactured for many years) contained 8MB of Flash and 32MB of RAM, many DD-WRT-capable devices today contain 4MB of Flash memory; a few models from certain manufacturers contain more flash (La Fonera, ASUS WL-500GP), some contain less (2MB). See Supported Devices.

Note that DD-WRT v24sp1 VPN builds have the JFFS feature removed, presumably due to conflicts that Brainslayer found between JFFS and bandwidth monitoring. See this thread for more information. Users interested in v24sp1 can opt:

  1. Use a build other than VPN, both MINI and MEGA still have JFFS
  2. Use an older build of DD-WRT
  3. Use a custom build, either homemade or dd-wrt.v24-10086_NEWD_openvpn_jffs_small.bin, which is described here as missing "snmp, all languages, some GUI styles and more.".

Flash Wear: A Warning

Take care not to store frequently changing files (i.e. often-changing log files) on Flash as this can cause flash wear-out over time.

  • A journalling flash file system is specifically designed to minimize frequent overwrites.
  • Files which are read many times but written infrequently work well on main flash.
  • Using the space provided by SD/MMC_mod places wear on replaceable secondary flash storage.

Directions for (normal) users: Web Interface

The steps to enable JFFS through the router web page are very specific. To avoid having to reset and reprogram your router, it's smart to make a backup here of your settings. If you follow these steps exactly, it should not lock up.

  1. On the router web page click on Administration.
  2. Scroll down until you see JFFS2 Support.
  3. Click Enable JFFS.
  4. Click Save.
  5. Wait couple seconds, then click Apply.
  6. Wait again. Go back to the Enable JFFS option, click Clean JFFS.
  7. Do not click "Save". Click Apply instead.

The router formats the available space, which is now shown in the JFFS2 Support box.

Directions for (freaky) Linux Gurus: CLI

Enter the following commands from the CLI:

nvram set jffs_mounted=1
nvram set enable_jffs2=1
nvram set sys_enable_jffs2=1
nvram set clean_jffs2=1
nvram set sys_clean_jffs2=1
nvram commit

Note: Device might reboot/hang after cleaning which might take long; be patient.


A user comments: I tried the previous commands under La Fonera firmware v24 RC4 and corrupted all my settings. I had to recover my unit with the procedures on La Fonera flashing page. I am not sure if this is a bug or these commands are not suited for La Fonera. Please try to use the web interface above. It works for me.

To unmount the JFFS:

nvram set sys_enable_jffs2=0
nvram set sys_clean_jffs2=0
nvram set jffs_mounted=0
nvram commit

Afterwards you can delete these variables with "nvram unset <variable>".

Options for Increasing JFFS Space

Add a 1GB flash memory card

  • Add the SD/MMC mod
    • up to (at least) 1GB storage using common swappable SD memory cards (built-in support with DD-WRT v2.4 and above).
    • create the folder /mmc/jffs
      mkdir /mmc/jffs
    • Use the Mount Bind command to point /jffs to the storage card:
      mount --bind /mmc/jffs /jffs
    • with v24 it appears you must have JFFS2 support enabled for this to work [to be confirmed]
    • Windows XP: WinSCP can be used to transfer files to and from the router, eliminating the need to pull the card out and put it in a card reader on a PC.
    • Linux, Mac OS X: Other SCP transfer applications exist.
    • Removed cards can be accessed natively in Linux or OS X, or on Windows with the Ext2FS driver [[1]].
    • On older firmware (v2.3), the limited JFFS space can be used to hold the drivers to load support for the SD card.

Add USB Storage

  • Routers with USB storage: A Linksys WRTSL54GS or ASUS WL-500g Premium device has USB capability (and more Flash and RAM). To enable USB on these devices see: USB_storage
    • Some firmwares (older): Drivers and startup files are stored in a small amount of JFFS space
    • Current firmware: USB support available within current v24 builds.
  • Using 24SP1 Mega on an Asus WL-500W with external USB HDD:
mount /dev/scsi/host0/bus0/target0/lun0/part1 /mnt
mkdir /mnt/jffs
mount /mnt/jffs /jffs

Using CIFS (Samba): Storing /jffs content remotely

One option is to create a share on the network and mount it on the router at /jffs using CIFS. Exact steps at CIFS


  • Enable JFFS or put the following command in a Script or Startup Command.
nvram set sys_enable_jffs2=1
  • Create a share on a CIFS-capable server called jffs.
    • Standard Microsoft Windows Shared Folder
    • Other operating systems may refer to SMB or Samba
  • In the Web GUI mount the CIFS share at /jffs.
  • Folder /jffs appears locally, while
  • Content actually saved remotely, on
    • NAS (Network Attached Storage)
    • Server (PC or some type of file server)


  •  ! Setting up a NAS or Server only for router maybe not economical.
    • Equipment Costs: Requires existing NAS or PC Server
    • Electricity Costs: if entire Server is only serving router
  • Availability Demands: CIFS share must be available
    • 24/7, or whenever the DD-WRT Device is on, and
    • Storing JFFS Share on quality equipment is required (i.e. Raid, Power Backup)
      •  ! Remote storage down means /jffs down, could mean DD-WRT Device down (increases the weak points).
  • Security Limitations: CIFS is limited to Microsoft's SMB protocol, offering up to only 128-bit security.
    • Poor Microsoft Protocol Security is not a problem if the LAN is physically and electronically protected from outside or inside intrusion (i.e. Guards, Guns, Locks, Dogs, Mines, Cameras, Firewalls)
  • LAN Connection Required: NAS cannot be wirelessly attached to DD-WRT Device.
  • Hassle: Using Microsoft Windows as the jffs Server
    •  ! Symbolic links in /jffs may not work.
    •  ! Rename (mv) commands on the /jffs mount may not work.

Most people only own an (inexpensive) Windows PC. A common Desktop PC does not a 24/7 Server make.

External Links:
Linux Newbies:

The following non-updated (as of 20080520) examples may be out of date:

  • CIFS was broken on many builds this update author tried. Although other people have reported it working - It may be a limitation of BusyBox CIFS when using NTLMv2 and 128-bit encryption.
  • (Mostly) only structural and spelling mistakes were corrected below (20080522)

Use a Startup Script: Example 1

  1. Read how to use Startup Scripts. Then place the following into your startup script to mount the JFFS partition:
umount /jffs #unmounts existing /jffs if existing
mount.cifs //<server's IP>/jffs /jffs -o username=<the username>,password=<the password>
nvram set sys_enable_jffs2=1 # fake-enable JFFS. Enable but do not commit. Makes ipkg think jffs2 is enabled.

NOTE: Username is Guest when hosted on Windows XP & 'Simple File Sharing' is enabled - This is the default on Windows XP Home.

Use Startup Scripts: Example 2

This method uses 2 scripts: The first will be started from /tmp/smbshare & mount the samba share under /jffs and start the other script. The second will be started from /jffs and unmount /tmp/sambashare.


  1. Enable CIFS (see also Jffs_sharing_in_a_Linux_server).
  2. Create a script called "" on the share:

#smb settings: same as the settings in the webgui
# change these to mount a different share than the current at /jffs
SMBSHARE=`nvram get samba_share`
SMBUSER=`nvram get samba_user`
SMBPASS=`nvram get samba_password`

#script to start in /jffs once we're done mounting

#where to log what is happening
export SMBLOG=/tmp/smblog
####### ok, here we go... ;) #######
echo "" > $SMBLOG
cd /

#make sure JFFS is unmounted.
echo "umounting /jffs if necessary..." >> $SMBLOG
umount /jffs >> $SMBLOG 2>&1

#mount our smbshare at /jffs
echo "mounting $SMBSHARE at /jffs..." >> $SMBLOG
mount.cifs $SMBSHARE /jffs -o username=$SMBUSER,password=$SMBPASS >> $SMBLOG 2>&1

#hand over startup to the JFFS part
/jffs/$JFFS_SCRIPT & >> $SMBLOG 2>&1

4. create a script called "" on the share:


#wait a sec, just to be sure the smb startup script has quit
sleep 1

#unmount the smbshare, its identical to /jffs now anyway :)
umount /tmp/smbshare

#to enable ipkg, we fake JFFS enabled.
#since theres no commit, this wont actually create a /jffs at Startup.
nvram set sys_enable_jffs2=1

#ready to do specific stuff, like starting services
#or other commands from /jffs

5. in the webinterface, enable CIFS with appropriate share/user/pass settings from step 2.

  • Enter "" as the script

6. Apply Changes
7. reboot

Now you should have the share configured in the web interface mounted at /jffs and should also be able to run 'ipkg' !

  • NOTE: If you are a Linux newbie, and you have problems with file permissions, look at this
  • Script files must be saved in UNIX format, not DOS. Windows editors that can do this are UltraEdit. EditPadPro and Crimson Editor, are free.
  • WinSCP can be used to easily change the execute flags on the scripts.

Use Startup Script: Example 3

This method requires 2 shares available for DD-WRT, but allows you to have 2 different areas of storage for the router. Some might find it useful. It is an amalgamation of the previous 2 methods.

Things you need:

  • 2 writeable shares on an NAS or Server.


1. Enable CIFS
2. Create a shell script in the network share, as follows:

nvram set sys_enable_jffs2=1 # fake-enable JFFS
umount /jffs # unmount /jffs if it exists
mount.cifs //<server's IP>/<jffs share name> /jffs -o username=<your username>,password=<your password>

3. Enter the name of the script in the CIFS-Samba startup script box in the Web Interface.
4. Apply changes.
5. Reboot

As an example network setup:

  • /tmp/smbshare located in a shared folder on the NAS called ddwrt, which contains scripts (including containing the above commands), yet to be installed packages and other static data
  • /jffs located in a shared folder called jffs, which contains program data for installed packages

Testing ipkg

Log in to the CLI (via Telnet or SSH) and enter the following commands:

mkdir -p /jffs/tmp/ipkg
ipkg update
ipkg list