[Planetlab-devel] RE: pl/xen

[Marc E. Fiuczynski]

Hi David,

For the benefit of others who are interested in PLXD, I am cc'in the devel
mailing list.

> We (David B. and I) have made some progress with PL/Xen.  David has an
> image he can boot on xen.  We were wondering about the vserver patches
> for xen.   The linux-vserver.org site doesn't have patches for the
> version of linux in xen-3.0.3.  Xen uses 2.6.16.29.   vservers has
> 2.6.14.3, 2.6.17.13 and 2.6.18.2.  Have you patched a Xen kernel with
> vservers?

I'm working on a 2.6.18 based kernel has xen support in it.  Not sure
whether that is xen 3.0.3 or older.  For the nodes to be PL compliant,
you'll need to use this kernel.

> We had some administrative questions as well:
>
> We'd like to put the PL image on our NetApp or NFS server so we can
> flash clone it when booting new PL nodes (using NFS or ISCSI roots for
> each node)?  Is there documentation about what node-specific state is
> in that image (so we could modify it for each new VM image)?  Would PL
> be amenable to this approach?  We don't seem to be able to use the
> boot manager b/c of kexec, so we'd like to boot a previously
> downloaded image----my understanding is this may affect PL software
> updates.  We may need a different method for updating our image until
> kexec is fixed.

As an aside: have you emailed the guy from SuSe and asked why his patch
appears incomplete?

Let me understand what you are trying to do:  you are trying to put the root
filesystem onto a NetApp server and the /vservers partition would also be on
this NetApp server?  I suppose using iSCSI would be the right way to do this
at first, because we use special filesystem tricks to get a poormans CoW for
our /vservers filesystem where all slice filesystems live.  The root fs used
by a PL node is fairly small (hundreds of MBs) and does get updated by code
running in the bootmanager upon boot.  Once the node is in production mode,
all node specific state then gets updated by the production kernel.

To make your experimentation and development easier, I strongly suggest that
you bring up a private PlanetLab (MyPLC) and work out all the details there
first before connecting your PLXD machines to the public PlanetLab.


> Can we add nodes to PL dynamically?  The administrative web interface
> has add node/remove node options.  Is there an XMLRPC interface to
> this?

Yes.  Look at the www.planet-lab.org/doc/api/plc_api documentation. Any
users with the PI / TECH roles can execute the AdmAddNode/AdmDeleteNode and
AdmGenerateNodeConfFile functions via XMLRPC.  Looks like David B. has the
tech role as part of his account at www.planet-lab.org.

Marc