Raspberry Pi: Moving !Boot to another drive

Introduction and rationale

By default, RISC OS for the Raspberry Pi has !Boot on the SD card, along with the boot loader partition. This is a low-cost way of providing the necessary storage, but there are drawbacks.

Having !Boot on the SD card means that the SD card will see lots of writes (thanks largely to the presence of !Scrap inside !Boot). An SD card was designed for use by devices such as digital cameras which would be writing a series of (say) 2MB files rather than the 1kB (or smaller) blocks being written by Filecore: this can result in the SD card performing substantially more write operations than expected.

Also, RISC OS does not implement the TRIM feature, so SD cards that support TRIM will not know when files have been deleted. This means that the wear-levelling algorithms won’t work as well as they could, leading to a reduced operating life.

In summary, you can improve SD card longevity by moving !Boot somewhere else.

Caveats

As the new boot disc will be connected by USB, it must be the only USB drive attached at boot time. This is because RISC OS looks for !Boot by drive number not drive name, and drive numbers could change following a reboot (the first disc to start up gets the lowest drive number). If you have more than one drive attached, they could start up in any order and RISC OS could look for !Boot on the wrong drive.

Preparatory work

If you have a Desktop Settings file, delete it. The file can be recreated, if necessary, after you have moved !Boot.

Procedure

1. Use !HForm to format the chosen device (e.g. SCSI::4) to Filecore format
2. Copy !Boot to the root directory of the chosen device
3. You will probably want to copy the other directories (Apps, Utilities etc.) as well.
4. Press F12 and issue the following two commands:
   *configure filesystem SCSI
*configure SCSIFSDrive 4
5. Reboot.

After moving !Boot

• You must retain !Boot.Loader on the SD card, but you can get rid of everything else once you are sure that the system is using !Boot on SCSI::4. Indeed, you can go the whole hog and replace the SD card with a (4GB maximum) FAT16-formatted card¹ containing only the files copied from !Boot.Loader.
• The copy of !Boot.Loader on the USB drive is surplus to requirements, so can be deleted.

¹ A FAT32 format card will boot, but RISC OS won’t be able to access the card when it’s in the SD slot. Among other things, this means that (1) the system clock will “jump backwards in time” after a shutdown and restart, and (2) changes to CMOS settings won’t survive a reboot. You can avoid these problems by ensuring that the first (or only) partition on the SD card is in FAT16 format (4GB maximum).