[Bug 1008228] New: SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Bug ID: 1008228
           Summary: SSD cache
           Product: Fedora Documentation
           Version: devel
         Component: release-notes
          Keywords: Tracking
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail], [e-mail],
                    [e-mail], [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail], [e-mail]
        Depends On: 998543, 999690, 1000817, 1001120, 1003208, 1000078,
                    1003207

+++ This bug was initially created as a clone of Bug #998543 +++

This is a tracking bug for Change: SSD cache
For more details, see: http://fedoraproject.org//wiki/Changes/SSD_cache

Using recent kernel (3.9 and later) features for (fast) SSD caching of (slow)
ordinary hard disks.

--- Additional comment from Rolf Fokkens on 2013-08-21 13:35:33 EDT ---

I'll build a bcache-tools RPM and a dm-cache-utils rpm (actually bcache-tools
is already available here: bcache-tools-20130820-0.1.fc19.src.rpm).

I'll follow the procedure as described here:
https://fedoraproject.org/wiki/Join_the_package_collection_maintainers

--- Additional comment from Rolf Fokkens on 2013-08-24 11:51:34 EDT ---

Tried to create a dmcache-utils package as well (Bug 1000078) but it doesn't
look really useful. So I'll focus on bcache-tools first. For that I still need
a sponsor.

--- Additional comment from Rolf Fokkens on 2013-08-27 06:52:40 EDT ---

I closed Bug 1000078 since good userland support requires LVM2 to support
dm-cache. Which will happen 'in the future', but F20 doesn't look feasible to
me.

--- Additional comment from Rolf Fokkens on 2013-08-31 16:21:30 EDT ---

Create Bug 1003207 (bcache support for dracut) which is not blocking for F20,
but probably will be blocking for F21.

--- Additional comment from Rolf Fokkens on 2013-08-31 16:25:06 EDT ---

Create Bug 1003208 (bcache support for anaconda) which is not blocking for F20,
but probably will be blocking for F21.

--- Additional comment from Rolf Fokkens on 2013-09-09 04:18:18 EDT ---

Test day planned: https://fedorahosted.org/fedora-qa/ticket/415

----------------------------------
Discussion at
https://lists.fedoraproject.org/pipermail/devel/2013-July/185336.html

Please document this Change in the Release Notes.

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #1 from Rolf Fokkens  ---
Are you refering to
http://fedoraproject.org/wiki/F20_Alpha_release_announcement?

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #2 from Pete Travis  ---
Rolf, this is for members of the Fedora Docs project to track representation of
your change in the Release Notes that are published at docs.fedoraproject.org
and shipped as the fedora-releaste-notes rpm. You don't have to do anything for
it, unless you want to. For your reference, we put content in
https://fedoraproject.org/wiki/Category:Documentation_beats?rd=Docs/Beats to
start, then a git repo later.

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #3 from Rolf Fokkens  ---
Not having to do anything is great :-)

The following may (or may not) be informational:

https://lists.fedoraproject.org/pipermail/devel/2013-September/189299.html

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Bug 1008228 depends on bug 999690, which changed state.

Bug 999690 Summary: Review Request: bcache-tools - Utility for manipulation Linux kernel block layer cache
https://bugzilla.redhat.com/show_bug.cgi?id=999690

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ON_QA                       |CLOSED
         Resolution|---                         |ERRATA

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Bug 1008228 depends on bug 1000817, which changed state.

Bug 1000817 Summary: Allow bcache devices to be used as PVs by default
https://bugzilla.redhat.com/show_bug.cgi?id=1000817

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ON_QA                       |CLOSED
         Resolution|---                         |ERRATA

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Bug 1008228 depends on bug 1001120, which changed state.

Bug 1001120 Summary: blkid & wipefs need bcache support
https://bugzilla.redhat.com/show_bug.cgi?id=1001120

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ON_QA                       |CLOSED
         Resolution|---                         |ERRATA

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #4 from Pete Travis  ---
draft at
https://git.fedorahosted.org/cgit/docs/release-notes.git/commit/?id=52418044...

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #5 from Rolf Fokkens  ---
As a suggestion I would also add http://bcache.evilpiepirate.org/ in the "Learn
more..." paragraph.

You may also think about the title. I agree that the title "SSD caching for
filesystems" may be best understood by most users, but all it really does is
speedup the underlying block device (which may be an abstract thing to may
users). And acceleration your filesystem is one of the applications, users may
also want to accelerate a logical volume thats supports a VM.

So maybe the title could be "SSD caching for filesystems an block devices".

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Nimimo  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

--- Comment #6 from Nimimo  ---
The Gentoo tutorial you link to has some warts (inaccuracies about block size
and conversion, and an ugly initramfs script), and the kylemanna link is about
dmcache not bcache.  I'm going to be peeved if this documentation perpetuates
the notion that existing devices can't be converted, by the way.  Please add a
link to https://github.com/g2p/blocks instead.

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #7 from Pete Travis  ---
Rolf, Nimimo, thanks for looking this over. I've made some changes based on
your input, and would appreciate your review.

https://git.fedorahosted.org/cgit/docs/release-notes.git/commit/?id=e70a05a4...

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #8 from Rolf Fokkens  ---
For Fedora 20 the blocks utility is not a part of bcache-tools, so the text is
not describing the Fedora 20 situation.

I would suggest the following text:

Fedora 20 offers experimental support for adding solid state drives (SSD's) as
fast, transparent caches to traditional rotating storage (HDD's). Filesystems
on the SSD cached block devices offer both the speed of SSD's and volume of
HDD's. In Fedora 20 SSD caching can be added to fresh partitions. Support for
adding SSD caching to existing standard partitions and LVM storage is planned
for Fedora 20"

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #9 from Pete Travis  ---
(In reply to Rolf Fokkens from comment #8)
> For Fedora 20 the blocks utility is not a part of bcache-tools, so the text
> is not describing the Fedora 20 situation.

I wondered about that. There's good information in that readme, but it might be
better left out to avoid confusion.
> I would suggest the following text:
>
> Fedora 20 offers experimental support for adding solid state drives (SSD's)
> as fast, transparent caches to traditional rotating storage (HDD's).
> Filesystems on the SSD cached block devices offer both the speed of SSD's
> and volume of HDD's. In Fedora 20 SSD caching can be added to fresh
> partitions. Support for adding SSD caching to existing standard partitions
> and LVM storage is planned for Fedora 20"

So, we can make a fresh bcache device *now*, and we expect subsequent updates
during the F20 cycle to allow adding cache to existing block devices?

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #10 from Rolf Fokkens  ---
My text should have been (typo)  "Support for adding SSD caching to existing
standard partitions and LVM storage is planned for Fedora 21" instead of "...
Fedora 20". But it's OK to make it "Support for adding SSD caching to existing
standard partitions and LVM storage is planned later during the Fedora 20
cycle"

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #11 from Pete Travis  ---
Rolf clarified this for me here, and out of band - thanks.

`blocks` looks like a great utility, but I'm not comfortable boasting that
Fedora offers it's functionality until `blocks` is formally packaged. I also
don't want to give the impression that existing block devices can't be
converted, but the integrity of the user's data is paramount. To that end, I've
added this admonition that I hope addresses everyone's concerns:

<note>
      <title>Make backups!</title>
      <para>
    Always back up your data before making low level changes, such as migrating
to a bcache device. Until tools like <ulink
url="https://github.com/g2p/blocks">blocks</ulink> are packaged for Fedora,
users are advised to implement bcache by creating clean bcache devices and
populating thier filesystems from a recent backup.
      </para>
    </note>

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

--- Comment #12 from Rolf Fokkens  ---
I checked out the latest fedora-release-notes package, looks good. Except for
the link to

http://blog.kylemanna.com/linux/2013/06/30/ssd-caching-using-dmcache-tutoria...

This link refers to dm-cache, which is an alternative to bcache. I think this
link should not be there, because it will confuse users.

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Bug 1008228 depends on bug 998543, which changed state.

Bug 998543 Summary: SSD cache
https://bugzilla.redhat.com/show_bug.cgi?id=998543

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ON_QA                       |CLOSED
         Resolution|---                         |CURRENTRELEASE

[Bug 1008228] SSD cache

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1008228

Pete Travis  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |CLOSED
         Resolution|---                         |CURRENTRELEASE
        Last Closed|                            |2014-01-26 16:46:43

--- Comment #13 from Pete Travis  ---
I've commented out that entry, thanks Rolf. It won't appear when next
published.