Andreas Dilger wrote:
On Jul 15, 2008 13:27 -0500, Jose R. Santos wrote:
On Mon, 14 Jul 2008 21:50:56 +0200
Goswin von Brederlow <goswin-v-b@xxxxxx> wrote:
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?
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.
Jose,
while waiting for the "efficient bitmap" support, how hard would it be
to implement "inefficient bitmaps" that just malloc some GB of memory
if needed? This would at least allow people with huge devices to test
mke2fs/ext4/e2fsck in the meantime.
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
I think that would be very useful - how much DRAM would we need for a
16TB file system ;-) ?
ric
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