which file system for sd card?
billk at iinet.net.au
Mon Jan 26 00:39:17 CET 2009
On Sun, 2009-01-25 at 15:15 +0100, Fernando Martins wrote:
> Pietro "m0nt0" Montorfano wrote:
> > William Kenworthy ha scritto:
> >> I found vfat clearly better (less susceptible to corruption) than ext2,
> >> however ext3 is better than vfat, but will still play up at times.
> >> Using it for OSM maps
> >> BillK
> > IMHO the best fs for sd is vfat if you don't care about permission, so
> > if you have to put your photos or docs on it, else ext2 is BETTER than
> > ext3 in this case for a simple reason, it doesn't have the journal.
> > Not having the journal imlies a redouced number of write to sd and a
> > reduced probability to get the data lost.
> I'm not sure I follow your logic favoring ext2. The point of ext3
> journal is exactly to control for errors. Even if you get globally more
> chance of errors with ext3, you should only consider the errors in the
> journal. I mean, a write to ext2 is equivalent to a write in ext3's
> journal, since from here, ext3 guarantees no errors in the fs, even if
> takes more tries to update it. So, if the transfer from the journal to
> the fs itself is guaranteed, then the comparison should be between ext2
> and the ext3's journal, right?
> Anyway, I'm also inclined for FAT, mostly for the simplicity (thus "less
> susceptibility to corruption") and universality of the fs. I'm just left
> wondering about performance, in particular as a storage for maps.
No, I favour ext3, with ext2 the worst of the lot. However, its
redundant as vfat wont handle ~840000 map tiles either without
continuing problems (large scale corruption, partitions going read only
part way through data transfers etc). It doesnt appear very good the
fact that a journal is needed to avoid corruption as a fact of normal
operation. Ive tried ext2/3 on dirvish server(s) and found a similar
problems - just poor/inadequate/inappropriate choice for this pattern of
data (OSM maps). Solution, reiserfs with data=journal ...
The consensus was you are very unlikely to kill a modern SD card. I
also did not see anyone who had actually been able to kill an SD card
from this reason.
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