Re: LFS Support

On Thursday 22 August 2002 05:37 am, The Eye wrote:
> On Wed, Aug 21, 2002 at 10:22:03PM -0500, Ken McGraw wrote:
> > Check out the article in the following link -
> > http://www.linuxgazette.com/issue55/florido.html
> >
> > There is a table several paragraphs down that compares the journaling
> > filesystems available for linux.  It confirms that Ext3FS has a
> > filesize limit of 2GB. THe filesystem can be 4 TB but a file is limited
> > too 2 GB.  The good news is that XFS (a favorite with the gentoo
> > folks), JFS and ReiserFS all seem to have much higher limits.
>
> Now I'm confused. see below for why:
>
> eye@lormoral generic-oe1 $ mount
> [..]
> /dev/hda6 on /home type ext3 (rw,noatime)
> [..]
> eye@lormoral generic-oe1 $ ls -lh jephtaamp.raw
> -rw-r--r--    1 eye      eye          2.3G Aug 21 01:38 jephtaamp.raw
> eye@lormoral generic-oe1 $
>
> i.e. filesystem mounted with ext3, got a file right here that's 2.3 Gig
> in size .. I'd have been very unpleasantly surprised had this not been
> possible, since it is the result of a live-recording-session.
>
> It'd be very strange anyway .. seeing as afaik ext3 is just an extension
> of ext2, which does support >2GB files ...


Interesting, I just got a file just over 3GB on ext3 when it filled the 
partition up. I haven't tried anything to verify the integrity of the file.

Looking at the header file for the ext3 file system the beginning of an inode 
looks like this -

struct ext3_inode {
        __u16   i_mode;         /* File mode */
        __u16   i_uid;          /* Low 16 bits of Owner Uid */
        __u32   i_size;         /* Size in bytes */
        __u32   i_atime;        /* Access time */
        __u32   i_ctime;        /* Creation time */
        __u32   i_mtime;        /* Modification time */
        __u32   i_dtime;        /* Deletion Time */
        __u16   i_gid;          /* Low 16 bits of Group Id */
        __u16   i_links_count;  /* Links count */
        __u32   i_blocks;       /* Blocks count */

This suggest it could support 4 GB files.  That doesn't say that there isn't a 
signed int32 someplace in the code or some other less obvious factor that 
could come into play.

My previous experience with XFS was on SGI boxes were it supported  very large 
files - I recall seeing 10G+ files.  I haven't tried it on linux so I can't 
say from personal experience what it supports although I recall seeing 
literature more than once that said it was capable of large files.

Ken