USB Stick as Swap Space (DiskStation)

  flip@ds106x ~/ssods/ssods-usbswap $ sudo mkdir /swap
  Password:
  flip@ds106x ~/ssods/ssods-usbswap $ sudo mount /dev/sdf4 /swap/
  Found partition:  b (Win95 FAT32) 
  flip@ds106x ~/ssods/ssods-usbswap $ sudo ./mkfile 4096 10240 /swap/swapfile
  file=/swap/swapfile, blocksize=4096, blocks=10240, size=40.0 MB
  flip@ds106x ~/ssods/ssods-usbswap $ sudo mkswap -v /swap/swapfile 
  Setting up swapspace version 0, size = 41938944 bytes
  flip@ds106x ~/ssods/ssods-usbswap $ sudo chmod 0600 /swap/swapfile 
  flip@ds106x ~/ssods/ssods-usbswap $ sudo ./swapon -v -p 1 /swap/swapfile 
  swapon on /swap/swapfile
  swapon: warning: /swap/swapfile has insecure permissions 0644, 0600 suggested
  flip@ds106x ~/ssods/ssods-usbswap $ cat /proc/swaps 
  Filename                        Type            Size    Used    Priority
  /dev/hda2                       partition       393584  72036   -1
  /swap/swapfile                  file            40956   0       1
  flip@ds106x ~/ssods/ssods-usbswap $ sudo ./swapoff -v /dev/hda2
  swapoff on /dev/hda2
  flip@ds106x ~/ssods/ssods-usbswap $ cat /proc/swaps 
  Filename                        Type            Size    Used    Priority
  /swap/swapfile                  file            40956   17012   1

Conclusions:

• Bloody DS
• USB Ports
  • The DS tries to mount sdX1
    • First drive (usually): sda (DS-106 series, system disk is hda), sdk (CS-406 series, system disks are sd[a-d]).
  • DS only tries to mount sdX1
  • if user selects «format» in the ds admin interface, the DS issues /sbin/sfdisk -N1 -uS -q -f --no-reread -o0 -z-1 -tb -F /dev/sdf (which fails if there is no sdX1 present), need to grok the command
    • one could probably have sdX1 and sdX4
• Swap to file on the cigar
  • basically works
  • need swapon and mkswap from util-linux
  • need a bigger cigar (128 MB or more)
  • need to figure out how this can be done automatically and in a stable way
    • maybe use internal usb port (see nslu2-linux.org)
    • how does the ds enumerate devices if ther is another usb device (e.g. a hdd) connected on boot?

Download ssods-usbswap-20061030.tar.gz

Ressources

• http://www.heise.de/ct/06/23/136/
• http://www.linuxfaq.de/f/cache/513.html
• http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/custom-guide/s1-swap-adding.html

Notes

The following command is probably faster than mkfile (creates a 100MB swap file):

dd of=swapfile bs=1024 count=0 seek=100k