Maximum ext3 file system size ??

[Andreas Dilger]

On Dec 06, 2004  14:54 -0800, Guolin Cheng wrote:
>  If the ext3 file system maximum size updated or it is still 4TB for
> 2.6.* kernel?  The site at
> http://batleth.sapienti-sat.org/projects/FAQs/ext3-faq.html says that it
> is 4TB yet, but I would like to know if it is possible to create and use
> stable & easy-to-fix (or at least as stable & easy-to-fix as ext3) file
> systems as big as 100TB for 32 bit Linux architecture?

I don't think it is practical to have such gigantic filesystems for ext3,
even if it would be possible.  Currently for ia64 and ppc64 and Alpha you
could use larger blocksize (up to 64kB) to give up to 2^31 * 64kB = 2^47
or 128TB filesystems without (I think) any changes.  We had reports of
one user trying to use a 4TB ext3 filesystem but there were problems when
they wrote more than 2TB (though it was unclear whether the problems were
from ext3, MD RAID, or the block/SCSI layer).

However, with such extremely large filesystems the e2fsck time would be
incredibly large I think (it grows with block count and inode count).

Not to be self-serving, but Lustre (which uses ext3 as the back-end
filesystem) has several customers running with 100TB+ filesystems and
will have a 900TB installation next year.  It can do this by aggregating
multiple independent ext3 filesystems together, and also scales the
number of fileservers so that you have better performance in addition
to just a very large single-server filesystem.  It isn't for everyone
(a GPL version is available, but it isn't trivial to set up/use yet) but
it is reliable enough to use on half of the world's largest Linux systems.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://members.shaw.ca/adilger/             http://members.shaw.ca/golinux/

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