On Tue, Oct 4, 2011 at 1:39 PM, Mick <michaelkintz...@gmail.com> wrote: > On Tuesday 04 Oct 2011 17:18:18 Paul Hartman wrote: >> You can create a real partition table on that device and reformat, if >> you want. (Note that some flash-based devices suffer degraded >> performance if you repartition or reformat them because they come with >> specially-aligned FAT tables from the factory) > > Interesting! I didn't know that. > > I have repartitioned USB sticks in the past, but did not notice any change in > performance - to be honest I didn't measure it. I assume then that if I were > to re-partition for any reason I would need to stick to exactly the same start > & finish shown by parted. > > Re-formatting it ought to be OK though, as long as the fat16 shown by parted > is correct.
I think filesystems other than FAT are aligned well already, assuming your partitions are aligned, but with FAT there are some hoops you must jump through. There is a tool called flashbench that can test your drive (destructively!) and figure out the most optimal block sizes. Here's a great article about it and optimizing USB flash drives in general: https://lwn.net/Articles/428584/ And here is a forum thread about figuring out the FAT alignment: http://www.patriotmemory.com/forums/showthread.php?3696 The SD council makes a tool for MS Windows that optimally formats and securely erases SD cards. Might be interesting to compare the results of its format to a standard fdisk and mkfs.vfat in linux. One thing I'm going to do next time I get a new SD card or flash drive is take a snapshot of the boot sector/partition tables/FAT tables so if I ever want to reformat it to FAT, I can restore the -- presumably optimal -- factory layout.
