Xen users - Nov 2007 - which disks/block device does Xen use at the moment?

I''m sending it again, as the message sent on 16.11.2007 didn''t
get to
the list.


Is there a way to guess which block devices / disk does Xen use at the 
moment?

I use Xen with iSCSI.
I connect to 50 iSCSI targets or more on each Xen server - and I get 
"virtual disks" ranging from /dev/sda to /dev/sdbl etc. -
it''s a lot.

Sometimes, I want to log out a given iSCSI connection (parameters 
changed on a target etc.) - but before I actually do it, I would like to 
know if that iSCSI drive is not used by Xen.

In other word - is there a way to check if Xen uses block device 
/dev/sda, /dev/sdu or /dev/sdbb etc.?


-- 
Tomasz Chmielewski
http://wpkg.org

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Tomasz Chmielewski wrote:
> I''m sending it again, as the message sent on 16.11.2007
didn''t get to
> the list.
>
>
> Is there a way to guess which block devices / disk does Xen use at the 
> moment?
>
> I use Xen with iSCSI.
> I connect to 50 iSCSI targets or more on each Xen server - and I get 
> "virtual disks" ranging from /dev/sda to /dev/sdbl etc. -
it''s a lot.
>
> Sometimes, I want to log out a given iSCSI connection (parameters 
> changed on a target etc.) - but before I actually do it, I would like 
> to know if that iSCSI drive is not used by Xen.
>
> In other word - is there a way to check if Xen uses block device 
> /dev/sda, /dev/sdu or /dev/sdbb etc.?
>
>
Well, what does "mount" say from the DomU, and what does "xm list
[DOMAIN] --long" say on the Dom0?

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Nico Kadel-Garcia schrieb:
> Tomasz Chmielewski wrote:
>> I''m sending it again, as the message sent on 16.11.2007
didn''t get to
>> the list.
>>
>>
>> Is there a way to guess which block devices / disk does Xen use at the 
>> moment?
>>
>> I use Xen with iSCSI.
>> I connect to 50 iSCSI targets or more on each Xen server - and I get 
>> "virtual disks" ranging from /dev/sda to /dev/sdbl etc. -
it''s a lot.
>>
>> Sometimes, I want to log out a given iSCSI connection (parameters 
>> changed on a target etc.) - but before I actually do it, I would like 
>> to know if that iSCSI drive is not used by Xen.
>>
>> In other word - is there a way to check if Xen uses block device 
>> /dev/sda, /dev/sdu or /dev/sdbb etc.?
>>
>>
> Well, what does "mount" say from the DomU
mount from domU would always say its "local" disk, that is, /dev/sda1
or
such. And good luck if domU is Windows.

> and what does "xm list 
> [DOMAIN] --long" say on the Dom0?
That''s it, certainly I can grep through that output, thanks!


Would be great if Xen registered some "holders" in /sys/block for a 
device it uses - like LVM or RAID does in /sys/block/<device>/holders/


-- 
Tomasz Chmielewski
http://wpkg.org

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Tomasz Chmielewski wrote:
> Nico Kadel-Garcia schrieb:
>> Tomasz Chmielewski wrote:
>>> I''m sending it again, as the message sent on 16.11.2007
didn''t get
>>> to the list.
>>>
>>>
>>> Is there a way to guess which block devices / disk does Xen use at 
>>> the moment?
>>>
>>> I use Xen with iSCSI.
>>> I connect to 50 iSCSI targets or more on each Xen server - and I
get
>>> "virtual disks" ranging from /dev/sda to /dev/sdbl etc. -
it''s a lot.
>>>
>>> Sometimes, I want to log out a given iSCSI connection (parameters 
>>> changed on a target etc.) - but before I actually do it, I would 
>>> like to know if that iSCSI drive is not used by Xen.
>>>
>>> In other word - is there a way to check if Xen uses block device 
>>> /dev/sda, /dev/sdu or /dev/sdbb etc.?
>>>
>>>
>> Well, what does "mount" say from the DomU
>
> mount from domU would always say its "local" disk, that is,
/dev/sda1
> or such. And good luck if domU is Windows.
Well, yes. I''m sorry if I was unclear: if you have multiple partitions 
mounted for whatever reason, this gives you a set of references for what 
the "xm list --long" says is available to the domain.
>> and what does "xm list [DOMAIN] --long" say on the Dom0?
>
> That''s it, certainly I can grep through that output, thanks!
Happy to oblige.
>
> Would be great if Xen registered some "holders" in /sys/block for
a
> device it uses - like LVM or RAID does in
/sys/block/<device>/holders/
Hmm. Interesting idea.

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Hi,

Maybe you''ll find these one-liners useful for your case, I''ve
wrote them for
machines that use image files as their disks:

for i in `xm list | grep -v Name | grep -v Domain | awk ''{print
$1}''`; do
vpath=`xm block-list $i | head -n 2 | tail -n 1 | awk ''{print
$7}''`; echo
$i: `xenstore-read $vpath/params`; done

In other words, I do
xm block-list domUname | awk ''{print $7}''
to get virtual paths for domU''s block devices and then
xenstore-read $vpath/params
to find out which image is in use.

You can also try
xenstore-read $vpath/node
I get a name of loop device that image is connected to through this line.

"Nico Kadel-Garcia" <nkadel@gmail.com> wrote in message 
news:4741B5C7.9010201@gmail.com...
> Tomasz Chmielewski wrote:
>> Nico Kadel-Garcia schrieb:
>> Would be great if Xen registered some "holders" in /sys/block
for a
>> device it uses - like LVM or RAID does in
/sys/block/<device>/holders/



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