The way I see block filter currently implemented is as a special block
device
with `is_filter` set to true.
Is this a correct characterization of the current incarnation?
If so, I was wondering if it is possible to insert a block filter layer
on top
of an existing block device once QEMU is
On Fri, Oct 11, 2013 at 11:38 AM, Eric Blake ebl...@redhat.com wrote:
On 10/11/2013 09:18 AM, Wolfgang Richter wrote:
Idea: Introduce a mode for drive-backup that duplicates writes to
another target, not CoW. It is useful for introspecting (my use
case), and for keeping a remote block device
On Sat, Oct 12, 2013 at 1:47 AM, Fam Zheng f...@redhat.com wrote:
While mirroring write is a good idea, doing it with drive-backup is probably
not. The function of this command is to 'backup' the image with existing data,
instead of new data. With your 'stream' mode, this semantic is changed.
Idea: Introduce a mode for drive-backup that duplicates writes to
another target, not CoW. It is useful for introspecting (my use
case), and for keeping a remote block device in sync with writes
(helps with migration or backup).
Issue with current modes: All of the current modes are
On Mon, Sep 30, 2013 at 3:41 AM, Paolo Bonzini pbonz...@redhat.com wrote:
Il 30/09/2013 00:46, Wolfgang Richter ha scritto:
All writes to the drive-backup source have to first copy the pre-write
data to the target. Thus, drive-backup usually works best if you are
using werror=stop
I wanted to explore overhead with the new drive-backup command and I
noticed if I set the target to something like '/dev/null' the guest VM
starts having IO errors and loses write access to its root file
system. Here is the qmp-shell command I'm using:
drive-backup sync=none device=virtio0
On Wed, May 15, 2013 at 7:54 AM, Paolo Bonzini pbonz...@redhat.com wrote:
But does this really cover all use cases a real synchronous active
mirror would provide? I understood that Wolf wants to get every single
guest request exposed e.g. on an NBD connection.
He can use throttling to
On Thu, May 16, 2013 at 9:44 AM, Richard W.M. Jones rjo...@redhat.comwrote:
Ideally I'd like to issue some QMP commands which would set up the
point-in-time snapshot, and then connect to this snapshot over (eg)
NBD, then when I'm done, send some more QMP commands to tear down the
snapshot.
On Wed, May 22, 2013 at 12:11 PM, Paolo Bonzini pbonz...@redhat.com wrote:
Essentially, if you're RWMJ (not me), and you're keeping a full
mirror, it's clear that the mirror write stream goes to an nbd server,
but is it possible to attach a reader to that same nbd server and read
things
On Wed, May 22, 2013 at 12:42 PM, Richard W.M. Jones rjo...@redhat.comwrote:
Run up to two extra guestfish instances, with the same result. The
fourth guestfish instance hangs at the 'run' command until one of the
first three is told to exit.
And your interested on being notified when a
I am in charge of a workshop happening at CMU with
21 guests currently registered.
It will be on using QEMU/KVM, coding inside those codebases,
using libvirt, and possibly OpenStack.
We will have several talks during the day on how people have
used QEMU + KVM in their own research, tips and
On Wed, May 22, 2013 at 3:26 PM, Richard W.M. Jones rjo...@redhat.comwrote:
On Wed, May 22, 2013 at 02:32:37PM -0400, Wolfgang Richter wrote:
On Wed, May 22, 2013 at 12:42 PM, Richard W.M. Jones rjo...@redhat.com
wrote:
Run up to two extra guestfish instances, with the same result
On Tue, May 14, 2013 at 4:40 AM, Stefan Hajnoczi stefa...@redhat.comwrote:
QEMU is accumulating many different approaches to snapshots and
mirroring. They all have their pros and cons so it's not possible to
support only one approach for all use cases.
The suggested approach is writing a
On Tue, May 14, 2013 at 4:50 AM, Kevin Wolf kw...@redhat.com wrote:
Or, to translate it into our existing terminology, drive-mirror
implements a passive mirror, you're proposing an active one (which we
do want to have).
With an active mirror, we'll want to have another choice: The mirror can
On Tue, May 14, 2013 at 6:04 AM, Paolo Bonzini pbonz...@redhat.com wrote:
Il 14/05/2013 10:50, Kevin Wolf ha scritto:
Or, to translate it into our existing terminology, drive-mirror
implements a passive mirror, you're proposing an active one (which we
do want to have).
With an active
On Tue, May 14, 2013 at 12:45 PM, Paolo Bonzini pbonz...@redhat.com wrote:
No, I'll just reuse the same hooks within block/mirror.c (almost... it
looks like I need after_write too, not just before_write :( that's a
pity). Basically:
1) before the write, if there is space in the job's
Paolo/anyone who knows -
Are drive-mirror sync points (NBD flush commands) reflecting guest write
barriers? Are guest write barriers respected by drive-mirror? If so, that
would make drive-mirror much more palatable for disk introspection work (a
drop-in usable feature of QEMU!).
--
Wolf
I'm working on a new patch series which will add a new QMP command,
block-trace, which turns on tracing of writes for a specified block device
and
sends the stream unmodified to another block device. The 'trace' is meant
to
be precise meaning that writes are not lost, which differentiates this
On May 13, 2013, at 5:46 PM, Richard W.M. Jones rjo...@redhat.com wrote:
On Mon, May 13, 2013 at 01:50:00PM -0400, Wolfgang Richter wrote:
Paolo/anyone who knows -
Are drive-mirror sync points (NBD flush commands) reflecting guest write
barriers? Are guest write barriers respected by drive
On Wed, Apr 24, 2013 at 4:37 AM, Stefan Hajnoczi stefa...@gmail.com wrote:
Has there been any performance analysis of drive-mirror (impact on
executing guest)?
It slows down guest I/O for a couple of reasons:
1. Writes now require a read from the original device followed by a
write to
On Wed, Apr 24, 2013 at 4:39 AM, Stefan Hajnoczi stefa...@gmail.com wrote:
On Tue, Apr 23, 2013 at 03:11:26PM -0400, Wolfgang Richter wrote:
On Tue, Apr 23, 2013 at 2:31 PM, Wolfgang Richter w...@cs.cmu.edu
wrote:
On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi stefa...@gmail.com
wrote
On Wed, Apr 24, 2013 at 5:24 AM, Paolo Bonzini pbonz...@redhat.com wrote:
Il 24/04/2013 10:37, Stefan Hajnoczi ha scritto:
Has there been any performance analysis of drive-mirror (impact on
executing guest)?
What Stefan wrote is about block-backup.
drive-mirror has a limited impact on
On Wed, Apr 24, 2013 at 5:26 AM, Paolo Bonzini pbonz...@redhat.com wrote:
Il 23/04/2013 20:31, Wolfgang Richter ha scritto:
On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi stefa...@gmail.com
mailto:stefa...@gmail.com wrote:
The tracing subsystem is geared towards tracepoint
On Wed, Apr 24, 2013 at 12:15 PM, Paolo Bonzini pbonz...@redhat.com wrote:
Il 24/04/2013 18:12, Wolfgang Richter ha scritto:
In the purest form, not to miss updates I'm not OK with it. But, I
think
that introspection can still _mostly_ work given these relaxed
constraints.
Reordered
On Wed, Apr 24, 2013 at 1:37 AM, Stefan Hajnoczi stefa...@gmail.com wrote:
I think what you really want is a tap block driver which mirrors
writes to a target device (typically a NBD volume). You can model this
on blkverify or check out Benoit Canet's quorum patches.
Stefan
An interesting
I'm interested in adding introspection of disk writes to QEMU for various
applications and research potential.
What I mean by introspection of disk writes is that, when enabled, each
write
passing through QEMU to backing storage would also be copied to an
introspection channel for further
On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi stefa...@gmail.com wrote:
The tracing subsystem is geared towards tracepoint instrumentation
rather than binary dumps.
Can you share some specific applications?
Well, my main application is in exposing a cloud-inotify service by
interpreting
On Tue, Apr 23, 2013 at 2:31 PM, Wolfgang Richter w...@cs.cmu.edu wrote:
On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi stefa...@gmail.comwrote:
Eric's suggestion to use NBD makes sense to me. The block-backup code
can be extended fairly easier using sync mode=none (do not perform
--
Wolf
On Apr 23, 2013, at 1:22 PM, Eric Blake ebl...@redhat.com wrote:
On 04/23/2013 11:12 AM, Wolfgang Richter wrote:
I'm interested in adding introspection of disk writes to QEMU for various
applications and research potential.
What I mean by introspection of disk writes is that, when
I am assuming the nics work with -user-net properties, with a simulated
router/firewall DHCP server at 10.0.2.2. Is it possible to manually
assign an IP (such as 10.0.2.5; is 10.0.2.3 still a nameserver?) and
still have access to the internet?
Wolfgang Richter wrote:
Basically, what I want
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