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Ubifs vs. Cramfs

Guru 20755 points
Hello, I read some of the tutorial about ubifs and cramfs, but I'm still not sure about some of the things... It seems reasonable to think that execution from ram is faster then execution from flash. But I did not see that it is said that cramfs is better in terms of execution time performance then ubifs. When I'm executing a utility in ubifs, does it actually copied to RAM and then executed ? Thank you very much, Ran
  • Ran,

    The major difference between the two is that Cramfs is a read-only file system while ubifs is a R/W file system. The motivation of using cramfs is whne you want to have a basic files system which is left intact and your system can always mount to it as it does not provide write permissions.

    In terms of performance the question would be if your file system is placed in NAND or RAM, this can be handled through the bootargs and bootcmd commends in u-boot. 

    The following links will assist you with more information.

    http://www.cyberciti.biz/files/linux-kernel/Documentation/filesystems/cramfs.txt

    http://www.linux-mtd.infradead.org/doc/ubifs.html

    Yair

  • Hi Yair, Thanks for the reply. I wanted to share my conclusions... ubifs which is succesor of jffs2, has many advantages on cramfs. When Nand is the place for filesystem, ubifs is defenetly better: it skip bad blocks, has power loss recovery, and it is writeable (advantage if we prefer writable filesystem). for my previous question, there is no need to copy files from ubifs to RAM before execution becuase anyway there is no really execution from nand, and it will be copies before to RAM. so cramfs defenetly loses in every aspect here... Regards, Ran