2011/4/21 funlw65(Vasi) <[email protected]> > Hi, > > I like the header of a .dbf file. Some database file systems use only > one file as a database for tables. It can be stored on a SD-Card as a > raw file withour ay file system? >
I'd say yes but you would have to "bypass" filesystem layer on your PC :) Maybe with "dd"... cheers, Seb > > On 21 apr., 09:19, Oliver Seitz <[email protected]> wrote: > > >>Some limitations are obvious: > > >>[...] > > >and no native support in existing OS, that would be the most important > limitation IMO... You could also just write data on sd-card, without any > filesystem at all > > > > Oh, yes, that limitation was so obvious that I even forgot to list it ;-) > > > > Sure, storing raw data to certain sectors is the easiest and also the > most common way. But if there is an unknown number of data sets, like sound > files for an audio player or recordings from a data logger, it would be > convenient to have some sort of grouping mechanism for data sets. > > > > The main criteria I have in mind when thinking about creating a new file > system is RAM usage while reading and writing of files. FAT takes at least > one sector of FAT (or a cached list of fragment positions) plus a sector of > user data. This is a quarter of the available RAM even for the largest 8-bit > PICs. And I'd like to have fast data transfer in linear mode. In my opinion, > random access can be a bit slower for most µC applications. > > > > I'll have a look at CP/M and C64 filesystems, but at least the C64 was > created for 180kByte media, so I fear it will not easily scale to 2GByte or > 1TByte... But I would have borrowed the way of storing "speaking" filenames: > Just define a file format for file #0, which associates a "numerical > filename" to a character string, that can be displayed as human-readable > filename. Other metadata, like file creation/modification/access time can go > there, too. > > > > For the OS support, userspace programs can be a start, but kernel modules > for linux and MacOS can be written. And for windows, noone expects > non-microsoft file systems to be supported ;-) > > > > Greets, > > Kiste > > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
