thanks, NTFS and utils [LWN.net]

thanks, NTFS and utils

Posted Feb 19, 2011 1:27 UTC (Sat) by pflugstad (subscriber, #224)
Parent article: Optimizing Linux with cheap flash drives

First and foremost, thank you for an excellent article. This is why I pay for LWN and it's payed off again.

I would think that with more and more systems using WinXP/Vista/7, many of these drives would start optimizing for NTFS instead of FAT, especially the higher-end SSDs. I don't know anything about NTFS, but presumably it doesn't have the same access pattens as FAT. I believe it has a log like ext3, right? Is this happening, or is that what the "data logging" drives are doing? Anyway to tell other than by testing which algorithms a drive uses?

Are there utils available for testing the layouts of drives and trying to optimize them for your usage pattern. Even something like whatever scripts were created to create the plots from this article would be useful I think. At a minimum, they can help you identify drives that are not optimized in a useful way.

Finally, other than optimizing partitioning and layout, are there benefit to using a filesystem such as logfs, jffs2, etc? (hmmm... can one even use them with a block device?)

Again, thanks for the article.

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thanks, NTFS and utils

Posted Feb 19, 2011 9:04 UTC (Sat) by arnd (subscriber, #8866) [Link]

For the extreme low end (SD cards, specifically), NTFS does not help because the SD card standard mandates not only the exact type of file system to be used (FAT16 up to 2 GB, FAT32 from 4 to 32 GB, ExFAT from 64 GB to 2 TB), but also the specific layout.

For USB sticks, the situation may be a little better because I've seen ads for ones that are allegedly optimized for NTFS. I have yet to get hold of those to find out what they do.

On the negative side, I have seen one USB stick with the typical FAT optimization (the second 4 MB segment being optimized for random access), which came preformatted with the FAT in another segment.

Regarding logfs, in theory it should be really well optimized for SSDs and it can work on a block device. Unfortunately, it's designed on the assumption that you can have around a dozen segments open at a time, which I have shown not to be possible on most media. However, if you can get the alignment and the layout right, logfs should still give you the best possible performance of the drive as long as you don't do a single fsync, at which point it will theoretically get into the worst case of thrashing.

jffs2 is completely useless on multi-gigabyte media, and does not really work on block devices.

ubifs on top of ubi on top of mtd on top of block2mtd on top of the block device might be an option, but stacking so many layers sounds scary to me.