Re: [Xen-devel] Re: [Xen-API] FT for XCP

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sun, Oct 09, 2011 at 01:16:46AM +0530, R J wrote:
>    Thanks Shriram,
> 
>    I thought of using the native VM migrate code but in that case I may end
>    up with corruption either in NW, DIsk or Mem.
>    The remus page is not updated. [1]http://nss.cs.ubc.ca/remus/hg/ I hope
>    this project is not stopped.
> 

There's also: http://wiki.xen.org/xenwiki/Remus

-- Pasi

>    I'm still learning xen-3.4.2/tools path so hopefully I'll get some
>    direction which can save from corruption.
> 
>    Regards,
>    R J
> 
>    On Wed, Sep 28, 2011 at 9:38 PM, Shriram Rajagopalan
>    <[2]rshriram@xxxxxxxxx> wrote:
> 
>      On Mon, Sep 26, 2011 at 8:58 AM, R J <[3]torushikeshj@xxxxxxxxx> wrote:
> 
>        Hello Mike,
> 
>        Thank you for suggestion. I would love to incorporate remus in xapi if
>        thats possible.
> 
>      Great. That would be certainly welcome. [I am not a fan of ocaml ;)]
> 
>        Remus as its inbuilt logic of detecting checkpoint failure and taking
>        decisions accordingly.
> 
>        I think there is remus support for xen 3.4
> 
>      What matters is the toolstack.
>      a. I am not sure if the xe toolstack uses libxenguest (tools/libxc) and
>       if it does, then it should have the basic remus support already.
> 
>      b. I am also not sure if it is recent enough to include all the remus
>      bug
>      fixes that went in over the last 6 months.
> 
>        What do you suggest as my next step ?
> 
>      Most of the remus code is python based and completely self contained. It
>      just needs
>      the domU's info (disk paths & vifs) as an s-expression. There is only
>      one api call to
>      Xend- to obtain the domU's s-expression.
> 
>      1. A quick and dirty way would be to change this single api call to xapi
>      equivalent
>      and obtain the s-expression, then you should have Remus running.
> 
>      2. Another approach would be to re-write the toolstack code in ocaml -
>      which might
>      be easy. But make sure that ocaml can make netlink api calls.
> 
>      shriram
> 
>        Regards,
>        Rushikesh
> 
>        On Mon, Sep 26, 2011 at 12:38 PM, Mike McClurg
>        <[4]mike.mcclurg@xxxxxxxxxx> wrote:
> 
>          On 09/25/2011 09:11 PM, R J wrote:
> 
>            Hello List,
> 
>            I have a proposal and wont mind to implement my self but need a
>            helping hand to start on.
>            I want to implement the aggressive FT feature in XCP. The best way
>            I could imagine is the use of feature *Live Migration*
> 
>            Steps
>            1. Enable the FT of a particular VM using xe commands and adding
>            as a param to that VM e.g. xe vm-param-set FT=true uuid=XYZ
>            2. If the FT = true detected by xenstore then xapi will initiate a
>            live migrate of that VM to any of available host.
>            3. A parallel "network ping"/"xapi heartbit" from/to that host
>            could be initialized for each FT VM.
>            4. Live migrate will run forever until its disabled by FT = false
>            or one of the host is down. e.g. the process will loop at 99.99%
>            migration state
>            5. If there is a packet drop of x packets the VM Migrate procedure
>            will mark the VM Migration as Complete and will switch the devices
>            forcefully.
>            -- this could result in some data loss but I dont have any
>            alternative to this.
>            -- The specific x packets can be set by XCP but we cant rely for
>            default XCP Errors
>            6. If there is a successful migration due to host down then we
>            will again start from step2
> 
>            Above steps I have assumed to my knowledge, we can discuss the
>            problems in it.
> 
>            Apologies if I'm being too naive.
> 
>            Regards,
>            Rushikesh
> 
>          This sounds like Remus ([5]http://nss.cs.ubc.ca/remus/). Are you
>          proposing to implement Remus support in xapi?
>          Mike
> 
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> References
> 
>    Visible links
>    1. http://nss.cs.ubc.ca/remus/hg/
>    2. mailto:rshriram@xxxxxxxxx
>    3. mailto:torushikeshj@xxxxxxxxx
>    4. mailto:mike.mcclurg@xxxxxxxxxx
>    5. http://nss.cs.ubc.ca/remus/
>    6. mailto:Xen-devel@xxxxxxxxxxxxxxxxxxx
>    7. http://lists.xensource.com/xen-devel

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