4K-sector drives and Fedora [LWN.net]

4K-sector drives and Fedora

Posted Mar 11, 2010 16:28 UTC (Thu) by msnitzer (subscriber, #57232)
In reply to: 4K-sector drives and Fedora by rahulsundaram
Parent article: 4K-sector drives and Linux

Here is another link that should give more insight on how most of the Linux I/O
stack has already been updated upstream and will be included in Fedora 13:
http://lkml.org/lkml/2010/3/11/230

I think it is unfortunate that the time was taken to highlight Linux's preparedness
for 4K sector drives but failed to accurately convey the true state of the various
pieces involved. Even inaccurately concluding that there is much work ahead for
the various Linux tools.

The article focused on Tejun's misunderstanding and worked from there rather
than incorporating the more promising state of Linux's preparedness that was
revealed in reply to Tejun's post.

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4K-sector drives and Fedora

Posted Mar 11, 2010 16:45 UTC (Thu) by corbet (editor, #1) [Link]

Interesting...I thought I wrote an article saying that, Tejun's worries notwithstanding, we're not in all that bad a shape. As far as I can tell, the only thing I got really wrong was regarding XP, which can handle things better than I had thought. As for the rest...what does it take to make a partitioning utility a little smarter?

Anyway, my apologies if you feel I misrepresented the situation.

4K-sector drives and Fedora

Posted Mar 11, 2010 17:09 UTC (Thu) by msnitzer (subscriber, #57232) [Link]

Hey Jon,

Not a big deal.. I was just saying that many of the partition tools and others have
already been updated. The "what does it take" to update them is somewhat
moot; as it has been done. Updating LVM was a bit more involved than
mkfs.ext3. Updating virtio and qemu was also somewhat intrusive.

But for those tools that haven't been updated they will either need to use libblkid
(like e2fsprogs does) or use the new "IO topology" block ioctls. Please see this
for more info (contains the specific ioctls and more):
http://people.redhat.com/msnitzer/docs/io-limits.txt

4K-sector drives and Fedora

Posted Mar 11, 2010 18:47 UTC (Thu) by ricwheeler (subscriber, #4980) [Link]

Thanks for the article!

One thing that seems to have been skipped in the discussion so far is that this is not just an issue with local, 4KB sector drives. The changes we have in the kernel and in the tool chain will help with external arrays which have long had larger internal "sectors" but pretended to have 512 byte sectors like a local disk.

The larger impact of the change is that it should all "just work" if we got all of the bits in place correctly :-)

Testing on a variety of storage hardware from various vendors, without and without DM and MD is really, really interesting right now to help us uncover any bits we did miss.