Re: ext4 64bit (disk >16TB) question

Jose R. Santos
2008-07-15T18:27:39Z

On Mon, 14 Jul 2008 21:50:56 +0200
Goswin von Brederlow <goswin-v-b@web.de> wrote:

> Hi,
>
> we are using lustre on a cluster of servers and raid boxes. Currently
> lustre is based on the ext3 code and has a limit of 8TiB for each
> filesystem. For us that results on having to split a servers storage
> into up to 4 chunks and run one fs on each which I would rather avoid.
> The solution for this would be to rebase the lustre patches to use
> ext4 instead, which should also reduce the patch set considerably.
> Lustre already patches a lot of ext4 features into the ext3 base.
>
>
> But before I start rebasing lustre I though I would first test out
> plain ext4 so I know any bugs I find will be from my rebasing and not
> already existing in ext4 itself. And there I run into a big problem:
> Current e2fsprogs (1.41) seem to be totaly unable to handle the ext4 64BIT
> feature, i.e. filesystems larger than 16TiB. The mkfs.ext4 always
> stops saying the disk exceeds the 32bit block count. And looking at
> the code I see a lot of blk_t (instead of blk64_t) and unsigned long
> (instead of unsigned long long [or even better blk64_t]) usage.
>
> I found ext4 64bit patches for e2fsprogs 1.39 that fix at least
> mkfs. Does anyone know if there is an updated patch set for 1.41
> anywhere? And when will that be added to e2fsprogs upstream?

Hi Goswin,

I've recently submitted a set of patches that covers most of the API
changes needed to support >16TB file systems (missing Ted bitmap
support of course). Once the bitmap support is included, it _SHOULD_
be relatively painless to add mke2fs support with this series of patches.

Stay tune.

> MfG
> Goswin

-JRS