bcache-tools and bcache support in other linux packages

Rolf Fokkens rolf at rolffokkens.nl
Mon Sep 30 15:04:04 UTC 2013


It was brought to my attention that there's a confusing typo in the
message below regarding the planning of bcache support for anaconda. The
claim that it is planned for F20 is not true, it is planned for F21:


Sorry for any confusion,


Op 26-09-13 11:56 schreef Rolf Fokkens <rolf at rolffokkens.nl>:

>Like I did on the 14th on the linux-bcache list I'd like to send an
>update on the progress of bcache related packages. While focussing on
>Fedora packaging of bcache-tools, I had some good collaboration with
>other packagers resulting in improved bcache support in other packages
>as well. Other Linux distro's may benefit from these updated packages too.
>On 27th of September util-linux v2.24 RC will probably be released. This
>release supports the identification of bcache superblocks in libblkid,
>actually integrating and obsoleting probe-bcache. Because of this udev
>rules for bcache can be simplified because they only need blkid. Of
>course this only applies to systems where util-linux v2.24 RC (or
>higher) actually is installed, otherwise probe-bcache is still needed.
>Since version 032 Dracut already had bcache support. Since version 033
>it adds support for util-linux v2.24 RC, so even without (obsoleted)
>probe-bcache it is able to identify bcache using blkid. Additionally
>Dracut benefits from blkid being able to identify bcache, because it
>uses blkid to identify all necessary kernel modules automatically, so no
>-N option is needed anymore.
>With the release of v2_01_102 LVM2 now accepts Physical Volumes on
>bcache by default. This simplifies the creation of initramfs (by Dracut)
>because no specific LVM2 option (--lvmconf) needs to be passed to
>Dracut.For the user this means that updating a kernel just works out of
>the box!
>The bcache-tools package is available in Fedora 20. I plan to build an
>updated package that no longer includes probe-bcache when the new
>util-linux is released.
>Anaconda (the Fedora installer) does not support bcache yet. This is
>planned for Fedora 20. This is important when installing Fedora on a
>system and having your root filesystem on bcache. Althought other
>Distro's don't use Anaconda, I guess their installers also need to be
>changed in some way to supportbcache.
>Currently having Fedora installed with your root Filesystem on bcache is
>possible, but It's done in a fewsteps:
>1. Install Fedora using Anaconda without using bcache, but create an
>extra partition to supportan alternate root FS
>2. From the running system build a bcache device using the extra
>partition. Copy the current root FS to the bcache root FS
>3. Reboot your system in the bcache root FS, and reclaim the spaces used
>by the non-bcache root partition
>More information can be found below, related to the "SSD Cache Fedora
>test day".
>The SSD Cache Fedora test day
>On 13th of October there's an "SSD Cache Fedora test day": see the Wiki
>page https://fedoraproject.org/wiki/Test_Day:2013-10-13_SSD_Cache. This
>page is work in progress, any feedback is welcome. People interested in
>testing are invited to participate on 13th of October.
>When there's anything new toreport, I'll keep you posted.
>Rolf Fokkens

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