Ext4 and large (>8TB) files

[Eric Sandeen]

Andreas Dilger wrote:
> On 2010-03-26, at 19:32, Arun Nair wrote:
>> Ok, so I guess ext4 with 64-bit, or another filesystem for us. Thanks
>> Andreas & Eric for all the help.
> 
> No, I don't think another filesystem will help, on a 32-bit host.  The
> limit that ext4 is reporting is the VM page cache limit for a single
> file, and has nothing to do with ext4 itself.

Well, for what it's worth, xfs doesn't use MAX_LFS_FILESIZE for s_maxbytes, and:

# mkfs.xfs -dfile,name=fsfile,size=5g
...
# mount -o loop fsfile  mnt/
# cd mnt/
# truncate --size 17592186044415 bigfile
# ls -lh bigfile
-rw-r--r--. 1 root root 16T Mar 29 14:03 bigfile
# uname -m
i686

it is possible to create a > 8T file offset.

Now, whether the vm is really happy with this probably remains to be seen;
this is the sort of thing that breaks without constant testing, IMHO.

I'd certainly suggest that a 64-bit box is the best way to go if at all possible.

-Eric