[dm-devel] Re: How to handle >16TB devices on 32 bit hosts ??

[Christoph Hellwig]

On Sat, Jul 18, 2009 at 04:21:56PM +0200, Andi Kleen wrote:
> > We don't have to rewrite fsck; most of the framework for supporting an
> > run-length-conding for compressed bitmaps is already in patches that
> > add > 32-bit block numbers to e2fsprogs; we've just been more focused
> > on getting 64-bit block numbers support merged than implementing
> > compressed bitmaps, but it's only one file that would need to be
> > added, and we might be able to steal the compressed bitmap support
> > from xfsprogs --- which does this already.
> 
> There are regular reports of xfs_repair failing on 32bit,
> even on volumes far smaller than 16TB.

We have a set of patches pending to reduce memory use in xfs_repair
dramaticly, replacing bitmaps for tracking used blocks with extent
structures stored in btrees.