Daniel P. Berrange wrote:
On Wed, Apr 08, 2009 at 05:53:57PM -0400, Dave Allan wrote:
Daniel P. Berrange wrote:
diff --git a/src/storage_conf.h b/src/storage_conf.h index 4e35ccb..cfd8b14 100644 --- a/src/storage_conf.h +++ b/src/storage_conf.h @@ -192,6 +192,12 @@ struct _virStoragePoolSource { /* Or an adapter */ char *adapter;
+ /* And an optional WWPN */ + char *wwpn; + + /* And an optional WWNN */ + char *wwnn; + Since adapter, wwpn and wwnn are all associated with each other, I think we should put them all into a union here. eg, replace the current
char *adapter;
with
union { char *name; char *wwpn; char *wwnn; } adapter; I don't have completely working code yet, but here's what I'm thinking:
We can't use a union because wwpn and wwnn will always be in use at the same time, but I agree that we're starting to collect a bunch of related information about adapters that clutters up the pool source struct. I've created a struct along the lines of virStoragePoolSourceHost to contain this information. It will need some additional fields.
I don't know what I was thinking when I wrote 'union'. I absolutely meant an anonymous 'struct'. A named struct as you show below is even better
/*
* For adapter based pools, info on the relevant adapter
*/ typedef struct _virStoragePoolSourceAdapter virStoragePoolSourceAdapter; typedef virStoragePoolSourceAdapter *virStoragePoolSourceAdapterPtr; struct _virStoragePoolSourceAdapter { char *name; char *wwpn; char *wwnn; };
Since we might be creating a virtual adapter on a physical adapter that we specify by wwpn/wwnn, we'll need two places to specify wwpn/wwnn in the XML. I propose:
Hmm, yes, this is what made me think originally that the storage pool may not be the right place to put the creation/deletion of the vport.
Working through the steps for using NPIV in our APIs...
- list of HBAs == virNodeListDevices() with cap='scsi_host'
- For each HBA - Query XML of the virNodeDevicePtr object - Look for 'vport' capability flag
You now have an virNodeDevicePtr object which you know is able to create/delete vports, lets say its name is 'host3'.
- Define config for a new vport, giving <parent> as the name of virNodeDevicePtr we just obtained
<device> <parent>host3</parent> <capability type='scsi_host'> <capability type='fc'> <wwpn>88889999aaaabbbb</wwpn> <wwnn>4444555566667777</wwnn> </capability> </capability> </device>
- Create the device with virNodeDeviceCreate(char *xml);
- Use the device by defining a SCSI storage pool using the <host></host> property of the device we just created
This keeps the notion of hierarchy / parent+child relationship between HBAs just witin the node device APIs, and avoids replicating it in the storage APIs.
The above generally sounds like a good idea to me. I am in the process of working out the specifics, but it's a much cleaner fit than trying to make this functionality go into pools.
I still think it would be worth adding a 'wwpn' and 'wwnn' to the SCSI storage pool XML config - to be used as an alternative to the 'host' parameter, since wwpn+wwnn are guarenteed stable across machines, whereas 'host' is only unique within scope of a single machine and even changes across boot.
That sounds good; a user can create the adapter with the device API and then be able to find the associated pool easily via wwpn/wwnn.
This does of course mean swe need to add new virNodeDeviceCreate and virNodeDeviceDestroy APIs, but I think it is worth doing that and they can be useful for other areas too. For example, it would allow us to have a means to create loopback devices, or create NBD devices (via qemu-nbd), which are useful things todo if you want to get into the innards of file based disks
Agreed.
<pool type="scsi"> <name>npiv</name> <source> <adapter name="host6" wwpn="0000111122223333" wwnn="4444555566667777"/> <vport wwpn="88889999aaaabbbb" wwnn="ccccddddeeeeffff"/>
So, we'd keep the <adapter> line as you show, but would not need the <vport> line, because the <adater> line would refer to the wwpn/wwn/host of the vport itself
That works for me.
</source> <target> <path>/dev/disk/by-id</path> </target> </pool>
Dave