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[Marco CONSONNI <mcocmo62@xxxxxxxxx>]

Sorry, the directory you need to check is  /var/lib/nova/instances.

MCo.

On Tue, Dec 4, 2012 at 5:54 PM, Marco CONSONNI <mcocmo62@xxxxxxxxx> wrote:

> Hi Ahmed,
>
> very technical questions.
> I'm not sure my answers are right: I'm just an user...
>
> In order to answer, I've just look at what happens and made some guess.
> Feel free to verify yourself.
>
> I'm assuming you are using KVM as I'm doing.
>
> The space for the boot disk and the ephemeral disk should be represented
> as files in the physical node where the VM is hosted.
> In order to check that, go to directory  /var/lib/nova on the node where
> the VM is running.
> As far as I understand, this is where nova (and KVM) keep the running
> instances' information.
> You should see a directory for each running instance named as
> instance-xxxxxxx, where xxxxxxx uniquely identifies an instance (there are
> several ways for uniquely identify an instance, this is one of many... but
> this is a different story).
> Go into one of these and check what you find.
>
> For what concerns nova-scheduler, I don't know what exactly does. I'm
> afraid that you need to test and see what happens.
>
> A nova command can help for inspecting what a node is using, in terms of
> resources.
>
> At the controller node (or any other node where you installed nova
> client), type the following command substituting OpenStack02 with the name
> of the node you want to inspect:
>
> *$ nova host-describe OpenStack02*
>
>
> +-------------+----------------------------------+-----+-----------+---------+
>
> | HOST        | PROJECT                          | cpu | memory_mb |
> disk_gb |
>
>
> +-------------+----------------------------------+-----+-----------+---------+
>
> | OpenStack02 | (total)                          | 16  | 24101     | 90
> |
>
> | OpenStack02 | (used_max)                       | 13  | 7680      | 0
> |
>
> | OpenStack02 | (used_now)                       | 13  | 8192      | 0
> |
>
> | OpenStack02 | 456ec9d355ae4feebe48a2e79e703225 | 4   | 2048      | 0
> |
>
> | OpenStack02 | fb434e07b687494bb669fde23f497970 | 9   | 5632      | 0
> |
>
>
> +-------------+----------------------------------+-----+-----------+---------+
>
> It return a brief report of the resources currently used by a node.
>
> To my knowledge,  the dashboard does not provide a similar page, at the
> time being.
>
> Hope it helps,
> Marco.
>
>
>
>
> On Tue, Dec 4, 2012 at 4:40 PM, Ahmed Al-Mehdi <ahmedalmehdi@xxxxxxxxx>wrote:
>
>> Hi Marco,
>>
>> Thank you very much for the info, much much clearer.  I was looking for
>> the boot disk using "ls -l /dev/sd*", but the existence of /dev/vda1
>> should have given me a clue.
>>
>> A few follow up questions:
>>
>> - I am assuming the space for the VM boot disk is allocated from the
>> local hard disk of the physical host on which the VM is instantiated,
>> right?
>> - If Yes
>>    - How is the boot disk represented on the physical host.  Is it a file
>> on the local filesystem that represent the VM boot disk?
>>    - I am guessing there is some logic in nova-scheduler that checs
>> first if there is enough disk apace on the physical host for the VM(along with RAM,
>> VCPUs) before launching the VM on the host?
>>    - Is there any way to find out from Horizon how much disk space is
>> available on a (or each) physical host for VM boot disk allocation?
>>
>> Thank you,
>> Ahmed.
>>
>>
>>
>>
>> On Tue, Dec 4, 2012 at 12:07 AM, Marco CONSONNI <mcocmo62@xxxxxxxxx>wrote:
>>
>>> Hello,
>>>
>>>
>>> When you use a flavor with an ephemeral disk size different from zero,
>>> the instance is booted with an extra virtual disk whose size is indicated
>>> by the ephemeral value (in GB).
>>>
>>> Using cirros image, try a flavor with ephemeral disk size different from
>>> zero (you need to create one yourself because the "standard" flavors have
>>> ephemeral size equal to 0), then log into the just booted instance and type:
>>>
>>>
>>> *$ ls /dev/vd**
>>>
>>> /dev/vda   /dev/vda1  /dev/vdb
>>>
>>>
>>>
>>> Disk /dev/vdb is a (virtual) disk, automatically created at boot time,
>>> corresponding to the ephemeral disk space indicated by the flavor . Please
>>> note that /dev/vda, mounted as /dev/vda1, is the boot disk, always created
>>> when you boot an instance.
>>>
>>> Verify the size of the available disks; more specifically, verify
>>> /dev/vdb:
>>>
>>> *
>>> *
>>>
>>> *$ sudo fdisk -l*
>>>
>>> Disk /dev/vda: 1073 MB, 1073741824 bytes
>>>
>>> 255 heads, 63 sectors/track, 130 cylinders, total 2097152 sectors
>>>
>>> Units = sectors of 1 * 512 = 512 bytes
>>>
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>>
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>>
>>> Disk identifier: 0x00000000
>>>
>>>
>>>
>>>    Device Boot      Start         End      Blocks   Id  System
>>>
>>> /dev/vda1   *       16065     2088449     1036192+  83  Linux
>>>
>>>
>>>
>>> Disk /dev/vdb: 1073 MB, 1073741824 bytes
>>>
>>> 16 heads, 63 sectors/track, 2080 cylinders, total 2097152 sectors
>>>
>>> Units = sectors of 1 * 512 = 512 bytes
>>>
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>>
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>>
>>> Disk identifier: 0x00000000
>>>
>>>
>>>
>>> Disk /dev/vdb doesn't contain a valid partition table
>>>
>>>
>>>
>>> Please note that /dev/vdb is made available as raw device, meaning that
>>> you need to partition and format it before using.
>>>
>>> You can find instructions on how to do that here
>>> http://docs.openstack.org/folsom/openstack-compute/admin/content/configure-nova-volume.html(search for command fdisk)
>>>
>>> Also note that this disk, being ephemeral, disappears when you terminate
>>> the VM. If you want to keep the data you produce with a VM that is destined
>>> to be terminated, you need to use Volumes that you explicitly create and
>>> attach using the services implemented by Cinder (former nova-volume).
>>>
>>>
>>> For what concerns the size you define for the boot disk, try and lunch
>>> two instances: one with flavor m1.tiny the other with m1.small:
>>>
>>>
>>> -- tiny --
>>>
>>> *$ sudo fdisk -l
>>> *
>>> Disk /dev/vda: 41 MB, 41126400 bytes
>>> 255 heads, 63 sectors/track, 5 cylinders, total 80325 sectors
>>> Units = sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>> Disk identifier: 0x00000000
>>>
>>>    Device Boot      Start         End      Blocks   Id  System
>>> /dev/vda1   *       16065       80324       32130   83  Linux
>>>
>>>
>>> -- small --
>>>
>>>
>>> *$ sudo fdisk -l
>>> *
>>> Disk /dev/vda: 21.5 GB, 21474836480 bytes
>>> 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
>>> Units = sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>> Disk identifier: 0x00000000
>>>
>>>    Device Boot      Start         End      Blocks   Id  System
>>> /dev/vda1   *       16065    41929649    20956792+  83  Linux
>>>
>>>
>>> As you notice, the size indicated by the flavor has effects on the size
>>> of the boot disk.
>>>
>>>
>>> Hope it helps,
>>> Marco.
>>>
>>>
>>>
>>>
>>> On Mon, Dec 3, 2012 at 7:03 PM, Ahmed Al-Mehdi <ahmedalmehdi@xxxxxxxxx>wrote:
>>>
>>>> Hello,
>>>>
>>>> I instantiated a VM using the cirros image, using the pre-defined
>>>> "m1.small" (1 VCPU, 2 GB Ram, 20G boot disk, 0 Ephemeral disk).  I then
>>>> logged into the console of the VM to view some system stats.  The num of
>>>> CPU and memory makes sense, but I am a bit confused on the storage aspect.
>>>>  I see the output of "df -h " as following:
>>>>
>>>> $ df -h
>>>> Filesystem              Size         Used            Available
>>>>  Use%     Mounted on
>>>> /dev                  1001.1M              0              1001.1M
>>>>   0%         /dev
>>>> /dev/vda1             23.2M        12.9M                   9.1M
>>>> 59%         /
>>>> tmpfs                1004.1M              0              1004.1M
>>>>   0%         /dev/shm
>>>> tmpfs                  200.0K        20.0K                180.0K
>>>> 10%         /run
>>>>
>>>>
>>>> What is the difference between Boot disk and Ephemeral disk?
>>>>
>>>> How can I correlate the 20G boot disk to the output of "df -h".
>>>>
>>>>
>>>> Regards,
>>>> Ahmed.
>>>>
>>>>
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>>>>
>>>
>>
>