[Kimchi-devel] [RFC] create a vm on a lun directly

[Rodrigo Trujillo]

On 03/17/2014 06:01 AM, Sheldon wrote:
> Now we have support iSCSI or SCSI pool.
> But we do not make use of the iSCSI or SCSI pool at present.

Yes, we do. Backend is ready, it is possible to pass the volume you want 
to user to VM when creating it.
Problem is that UI is not ready (actually, I had developed, it worked, 
but it was not accepted, so we are waiting
from UI guys).

>
> Here we want to create volumes for VM in those pools.
> The best way to do it is on template level - and not on vm level

I had a lot of discussions with Aline about this. Volumes in iSCSI and 
SCSI (Fibre Channel) pools cannot be done via libvirt.
They should be created outside of Kimchi by the administrators.
Also, due to the architecture of Kimchi, we cannot mix disks from 2 
different types of storage pools, for instance: I cannot
have a vm with 2 disks, where one comes from a SCSI pool and other is a 
.img in a DIR pool.

>
> For if we create a template just assign a iSCSI or SCSI pool, the user 
> still need to choose
> a volume for his VM.
>
> in the edit template page, we list the storage pool and the volume
> like:
> dir-pool-1
> nfs-pool-2
> iscsi-pool-1/lun-1
> iscsi-pool-1/lun-2
> iscsi-pool-1/lun-3
> scsi-pool-1/lun-1
> scsi-pool-1/lun-2
>
> when selecting the storage pool with type iSCSI or SCSI the user also 
> select the volume.

I have to agree with Ming, this does not makes sense... it is the same 
that create a .img in template level and
left it assigned forever in the template. User would need to create a 
new template for each volume or edit the
template for each new VM he wants to create.

> The user can create a VM with this volume.
>
> But we should let user know it is dangerous to avoid user mistake when 
> he choose the volume.
>
> 1. Now we only use the volume to create the vm not support shareable 
> volume.
> use the same volume in multiples vms, a new install will overwrite the 
> current content.
> We can check the volume ref_cnt to avoid this.
>
> 2. even this lun is not used buy vm, maybe the Adam has added a lun to 
> a VG or use it on other purpose
> Should we check the lun is is used external kimchi?
> If a lun is added to a VG, need to check it?
> If adam format a lun and create a files system on, need to check it?
> Or we just prompt the data on this volume will destroyed.


Regarding SCSI (Fibre Channel) and,  probably, iSCSI  pools .... I know 
that what is missing is to use the LUNs as
Filesystem pools. So, the LUN will store the disk images used by VMs.