File system for compact flash or SD for linux to run off of.

Michael Torrie torriem at gmail.com
Wed Aug 31 19:07:24 MDT 2011


On 08/31/2011 06:24 PM, Tod Hansmann wrote:
> We had a situation at work where we are working with an embedded linux 
> device and have to use an SD card for the filesystem.  After a bunch of 
> benchmarking, we chose ext4 and now have a 32GB class 10 SD card working 
> at about 7-9 MB/s writing (which was our only concern.  Reading can go 
> slower than 2MB/s for all we care, but I'm pretty sure its performance 
> is equally good.)
> 
> The trick was we had to disable extents, and possibly play with the 
> block size, but I don't recall on the latter.  YMMV, but I think you'll 
> like ext4's performance.

Sounds like good advice.  Right now, I'm testing a setup with an ext4
boot partition and a btrfs root partition.  I've set up tmpfs for things
in /var like /var/run, /var/lock, etc.  If this goes into production I
think I'll drop syslog completely.  So overall this might work.  I'd
like to keep the root filesystem writeable so we can do updates and
maintenance (at least during the trial run) while the computer is in
operation controlling a piece of equipment.

In the long run, read-only ext4 combined with tmpfs just might be the
ticket.  But I'm hopeful that btrfs will work as well, because it has
some flash memory considerations (at least the CF and SD kind).


I'll let folks know how it goes.


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