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Xenstore data not getting updated in running VM

 

 

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torushikeshj at gmail

Jan 18, 2012, 6:31 AM

Post #1 of 6 (753 views)
Permalink
Xenstore data not getting updated in running VM

Hello List,

I'm not able to fetch correct xenstore data in guest. If I reboot the guest
then it loads with latest xenstore data but if I change the content of
xenstore data while the VM is running then the data does not reflect in
guest.

Is this normal or am I missing anything ?


Note: XCP version 1 and guest tools are installed.

- RJ


george.shuklin at gmail

Jan 19, 2012, 4:14 AM

Post #2 of 6 (735 views)
Permalink
Re: Xenstore data not getting updated in running VM [In reply to]

What 'correct data' you mean? If you write data/foo "bar" from domU you
can read them from dom0 as /local/domain/$domid/data/foo

On 18.01.2012 18:31, R J wrote:
> Hello List,
>
> I'm not able to fetch correct xenstore data in guest. If I reboot the
> guest then it loads with latest xenstore data but if I change the
> content of xenstore data while the VM is running then the data does
> not reflect in guest.
>
> Is this normal or am I missing anything ?
>
>
> Note: XCP version 1 and guest tools are installed.
>
> - RJ
>
>
> _______________________________________________
> xen-api mailing list
> xen-api [at] lists
> http://lists.xensource.com/mailman/listinfo/xen-api


torushikeshj at gmail

Jan 19, 2012, 8:33 AM

Post #3 of 6 (728 views)
Permalink
Re: Xenstore data not getting updated in running VM [In reply to]

On Thu, Jan 19, 2012 at 5:44 PM, George Shuklin <george.shuklin [at] gmail>wrote:

> What 'correct data' you mean? If you write data/foo "bar" from domU you
> can read them from dom0 as /local/domain/$domid/data/foo
>

I'm using API VM.add_to_xenstore_data to add data to a running domU which
is reflected in
xe vm-param-get param-name=xenstore-data uuid=UUID_OF_VM but if I do
"xenstore-ls data" in domU then it does not reflect the updated/new entries.

If I reboot the domU then it is able to show updated entries with same
"xenstore-ls data" command.


>
> On 18.01.2012 18:31, R J wrote:
>
> Hello List,
>
> I'm not able to fetch correct xenstore data in guest. If I reboot the
> guest then it loads with latest xenstore data but if I change the content
> of xenstore data while the VM is running then the data does not reflect in
> guest.
>
> Is this normal or am I missing anything ?
>
>
> Note: XCP version 1 and guest tools are installed.
>
> - RJ
>
>
> _______________________________________________
> xen-api mailing listxen-api [at] listshttp://lists.xensource.com/mailman/listinfo/xen-api
>
>
>
> _______________________________________________
> xen-api mailing list
> xen-api [at] lists
> http://lists.xensource.com/mailman/listinfo/xen-api
>
>


Dave.Scott at eu

Jan 19, 2012, 8:58 AM

Post #4 of 6 (740 views)
Permalink
Re: Xenstore data not getting updated in running VM [In reply to]

Hi,

At the moment "add_to_xenstore" data isn't 'live': a reboot (or migrate) is required to refresh it.

What kind of data are you using xenstore for? It tends to be good for rarely-changing configuration data but bad for anything which updates frequently. It's also a bit 'fire and forget' while people often want something like an RPC interface.

Cheers,

--
Dave Scott

On Jan 19, 2012, at 4:35 PM, "R J" <torushikeshj [at] gmail<mailto:torushikeshj [at] gmail>> wrote:



On Thu, Jan 19, 2012 at 5:44 PM, George Shuklin <george.shuklin [at] gmail<mailto:george.shuklin [at] gmail>> wrote:
What 'correct data' you mean? If you write data/foo "bar" from domU you can read them from dom0 as /local/domain/$domid/data/foo

I'm using API VM.add_to_xenstore_data to add data to a running domU which is reflected in
xe vm-param-get param-name=xenstore-data uuid=UUID_OF_VM but if I do "xenstore-ls data" in domU then it does not reflect the updated/new entries.

If I reboot the domU then it is able to show updated entries with same "xenstore-ls data" command.



On 18.01.2012 18:31, R J wrote:
Hello List,

I'm not able to fetch correct xenstore data in guest. If I reboot the guest then it loads with latest xenstore data but if I change the content of xenstore data while the VM is running then the data does not reflect in guest.

Is this normal or am I missing anything ?


Note: XCP version 1 and guest tools are installed.

- RJ



_______________________________________________
xen-api mailing list
xen-api [at] lists<mailto:xen-api [at] lists>
http://lists.xensource.com/mailman/listinfo/xen-api



_______________________________________________
xen-api mailing list
xen-api [at] lists<mailto:xen-api [at] lists>
http://lists.xensource.com/mailman/listinfo/xen-api


_______________________________________________
xen-api mailing list
xen-api [at] lists<mailto:xen-api [at] lists>
http://lists.xensource.com/mailman/listinfo/xen-api


george.shuklin at gmail

Jan 19, 2012, 10:17 AM

Post #5 of 6 (729 views)
Permalink
Re: Xenstore data not getting updated in running VM [In reply to]

Ah, ok, you didn't mention XenAPI. Those fields is not a 'real time
communication way'. If you need to have it, you need to create your own
xenstore-based application to be ran in dom0. Or create xapi plugin for
this.

This is not really 'API-like', but my experience (we performs about
100-150 writes/reads per second on every host in cloud) says this is
single way to have nice real-time communication with domU via xenstore.

pitfall:
Note that VM can reboot itself (new domain - no 'foreign' data in
xenstore). Same for migration - every migration move VM to new domain.

On 19.01.2012 20:33, R J wrote:
>
>
> On Thu, Jan 19, 2012 at 5:44 PM, George Shuklin
> <george.shuklin [at] gmail <mailto:george.shuklin [at] gmail>> wrote:
>
> What 'correct data' you mean? If you write data/foo "bar" from
> domU you can read them from dom0 as /local/domain/$domid/data/foo
>
>
> I'm using API VM.add_to_xenstore_data to add data to a running domU
> which is reflected in
> xe vm-param-get param-name=xenstore-data uuid=UUID_OF_VM but if I do
> "xenstore-ls data" in domU then it does not reflect the updated/new
> entries.
>
> If I reboot the domU then it is able to show updated entries with same
> "xenstore-ls data" command.
>
>
>
> On 18.01.2012 18:31, R J wrote:
>> Hello List,
>>
>> I'm not able to fetch correct xenstore data in guest. If I reboot
>> the guest then it loads with latest xenstore data but if I change
>> the content of xenstore data while the VM is running then the
>> data does not reflect in guest.
>>
>> Is this normal or am I missing anything ?
>>
>>
>> Note: XCP version 1 and guest tools are installed.
>>
>> - RJ
>>
>>
>> _______________________________________________
>> xen-api mailing list
>> xen-api [at] lists <mailto:xen-api [at] lists>
>> http://lists.xensource.com/mailman/listinfo/xen-api
>
>
> _______________________________________________
> xen-api mailing list
> xen-api [at] lists <mailto:xen-api [at] lists>
> http://lists.xensource.com/mailman/listinfo/xen-api
>
>


torushikeshj at gmail

Jan 19, 2012, 1:41 PM

Post #6 of 6 (737 views)
Permalink
Re: Xenstore data not getting updated in running VM [In reply to]

Thanks George and Dave for explanation. I was trying to implement a live
password reset utility.
I think I'll force VM to reboot which is working :)

Cheers,
RJ

On Thu, Jan 19, 2012 at 11:47 PM, George Shuklin
<george.shuklin [at] gmail>wrote:

>
> Ah, ok, you didn't mention XenAPI. Those fields is not a 'real time
> communication way'. If you need to have it, you need to create your own
> xenstore-based application to be ran in dom0. Or create xapi plugin for
> this.
>
> This is not really 'API-like', but my experience (we performs about
> 100-150 writes/reads per second on every host in cloud) says this is single
> way to have nice real-time communication with domU via xenstore.
>
> pitfall:
> Note that VM can reboot itself (new domain - no 'foreign' data in
> xenstore). Same for migration - every migration move VM to new domain.
>
>
> On 19.01.2012 20:33, R J wrote:
>
>
>
> On Thu, Jan 19, 2012 at 5:44 PM, George Shuklin <george.shuklin [at] gmail>wrote:
>
>> What 'correct data' you mean? If you write data/foo "bar" from domU you
>> can read them from dom0 as /local/domain/$domid/data/foo
>>
>
> I'm using API VM.add_to_xenstore_data to add data to a running domU which
> is reflected in
> xe vm-param-get param-name=xenstore-data uuid=UUID_OF_VM but if I do
> "xenstore-ls data" in domU then it does not reflect the updated/new entries.
>
> If I reboot the domU then it is able to show updated entries with same
> "xenstore-ls data" command.
>
>
>>
>> On 18.01.2012 18:31, R J wrote:
>>
>> Hello List,
>>
>> I'm not able to fetch correct xenstore data in guest. If I reboot the
>> guest then it loads with latest xenstore data but if I change the content
>> of xenstore data while the VM is running then the data does not reflect in
>> guest.
>>
>> Is this normal or am I missing anything ?
>>
>>
>> Note: XCP version 1 and guest tools are installed.
>>
>> - RJ
>>
>>
>> _______________________________________________
>> xen-api mailing listxen-api [at] listshttp://lists.xensource.com/mailman/listinfo/xen-api
>>
>>
>>
>> _______________________________________________
>> xen-api mailing list
>> xen-api [at] lists
>> http://lists.xensource.com/mailman/listinfo/xen-api
>>
>>
>
>

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