Samsung RFS Filesystem
Hi,
I would maybe interested in testing the Samsung RFS File System...
Does someone, here, already used it, and what are the conclusions ?
Thank you very much.
Ludovic.
Quoted 5 lines · Ludovic Guilhamat
Hi,
I would maybe interested in testing the Samsung RFS File System...
Does someone, here, already used it, and what are the conclusions ?
Please do do some testing. It would be good to see the results, positive or negative.
I have not used it, but from a description I can draw some immediate conclusions.
RFS = Robust FAT file system
Quoted 1 line
From the blurb at
http://www.samsung.com/Products/Semiconductor/Flash/TechnicalInfo/rfs.htm
this looks a bit like FATFS running on top of DOC. It might have some transactioning which would make it look a bit more like Microsoft's TFAT.
Neither of these are a proven reliable system. DOC can still get FAT corruptions if you don't umount before power loss (== potentially a completely scrambled fs). TFAT is completely unprovedn and is slower and not always robust (not robust with typical mount options). Perhaps RFS gets the robustness right.
Running FAT on NAND costs some performance due to the FTL etc. To make a journaling system on FAT, as RFS claims, costs even more performance.
IMHO: If you want robustnes on NAND use a log structured fs designed for
flash: YAFFS or JFFS2.
For completeness, I will state that I wrote YAFFS, but I don't think this biases my answer.
-- CHarles
Quoted 26 lines · Charles Manning
Quoted 7 lines · Ludovic Guilhamat
Hi,
I would maybe interested in testing the Samsung RFS File System...
Does someone, here, already used it, and what are the conclusions ?
Please do do some testing. It would be good to see the results, positive or negative.
I have not used it, but from a description I can draw some immediate conclusions.
RFS = Robust FAT file system
Quoted 1 line
From the blurb at
http://www.samsung.com/Products/Semiconductor/Flash/TechnicalInfo/rfs.htm
this looks a bit like FATFS running on top of DOC. It might have some transactioning which would make it look a bit more like Microsoft's TFAT.
Neither of these are a proven reliable system. DOC can still get FAT corruptions if you don't umount before power loss (== potentially a completely scrambled fs). TFAT is completely unprovedn and is slower and not always robust (not robust with typical mount options). Perhaps RFS gets the robustness right.
Quoted 10 lines
Running FAT on NAND costs some performance due to the FTL etc. To make a journaling system on FAT, as RFS claims, costs even more performance.
IMHO: If you want robustnes on NAND use a log structured fs designed for flash: YAFFS or JFFS2.
For completeness, I will state that I wrote YAFFS, but I don't think this biases my answer.
-- CHarles
Thanks.
Actually, the system I work on uses Jffs2 (Coldfire with uClinux). But, mount times are very long (the memory is a Flash Nand 16Mb). So, I planned to test Jffs2 patches (from the Jffs2 Improvement Project), then Yaffs. And as RFS is not freely distributed, and I don't know yet its cost, I wanted to know if someone had tested it.
Thanks for your response.
Ludovic.
Quoted 6 lines
Actually, the system I work on uses Jffs2 (Coldfire with uClinux). But, mount times are very long (the memory is a Flash Nand 16Mb). So, I planned to test Jffs2 patches (from the Jffs2 Improvement Project), then Yaffs. And as RFS is not freely distributed, and I don't know yet its cost, I wanted to know if someone had tested it.
Pick up a more recent JFFS2, I believe that there have been some speedups.
I get a lot of feedback that YAFFS is typically a few times faster than JFFS2
FAT is indeed "instant mounting" and uses less RAM because it is not log structured. FAT however does have a bad record as far as reliability and write speed on raw NAND devices.
In the end you need to look at pros and cons and fit them to your system needs.
-- Charles