Xen API and PSCSI Devices

[Joshua West <jwest@brandeis.edu>]

Hey folks,

I've noticed that, when using the Xen API, results returned by examining
the list of PSCSI's available to Xen is not updated between calls.  It
seems that PSCSI devices are detected once and only once -- upon startup
of xend.

An example of what I'm discussing is:

[root@some-xen-server:~]# python
Python 2.4.3 (#1, Jun 11 2009, 14:09:37)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import xen.xm.XenAPI as XenAPI
>>> session = XenAPI.Session('http://127.0.0.1:9363')
>>> session.login_with_password('', '')
>>> session.xenapi.PSCSI.get_all()
['45df9686-2da7-52a1-98a0-8a944273d559',
'72bea6df-0fc4-0643-42e8-a5adf07780d7']

...
Attach a new LUN to the host (dom0).
...

>>> session.xenapi.PSCSI.get_all()
['45df9686-2da7-52a1-98a0-8a944273d559',
'72bea6df-0fc4-0643-42e8-a5adf07780d7']

The new LUN is not detected, unless you restart xend.  Is this a bug? 
Or by design?  It would be really nice if the API were to refresh the
list of PSCSI devices detected during each call... or at least have an
API method to instruct xend that it should refresh its listing?

BTW -- I'm doing this on RHEL 5.4 x86_64 with Xen 3.4.1.

Thanks.

-- 
Joshua West
Senior Systems Engineer
Brandeis University
http://www.brandeis.edu