ext2 large_file

[Ivan Voras]

On Tue, 1 Nov 2005, Bruce Evans wrote:

> Unless the file system already has or had a large file.  Possible
> workarounds:
> (1) Boot Linux and create a large file.  Hopefully e2fsck only sets the
>    flag so you only have to do this once.

I did this but e2fsck doesn't set the flag. Fortunately, I found out that 
e2fsprogs includes "debugfs" utility with which I manually set the flag.

It works now!

ext2 filesystem access is still a bit slower than with WindowsXP with
ext2+ext3 IFS driver (~20.5MB/s vs ~25MB/s). The reason I brought up this 
subject is that I'm experimenting with using ext2 instead of msdosfs for 
exchanging data between the systems in dual-boot configuration. Because 
ext2 large_file support works now, I think it's much more safer and even 
somewhat faster (less fragmentation! FreeBSD's msdosfs looks like it's
pessimized for fragmentation!) to use instead.

I propose this patch to the mount_ext2fs manual page:

--- mount_ext2fs.8_old	Mon Oct 31 20:43:17 2005
+++ mount_ext2fs.8	Mon Oct 31 20:56:45 2005
@@ -60,6 +60,21 @@
  .Xr mount 8
  man page for possible options and their meanings.
  .El
+.Sh BUGS
+Unlike the original Linux implementation, the "large_file"
+flag is not set automatically when first file larger than
+2GB is created. Instead,
+.Xr debugfs 8
+utility from the e2fsprogs port must be used to manually
+set the flag with `feature large_file` command. Other than
+this, large files are fully supported.
+
+Support for journaling (ext3) is missing, and filesystems that
+have it enabled are treated as plain ext2 filesystems.
+This means that
+.Xr e2fsck 8
+will have to be used to repair the journal when the filesystem
+is to be used in Linux.
  .Sh SEE ALSO
  .Xr mount 2 ,
  .Xr unmount 2 ,