Open Stack

Hi guys, i'd like to know your opinions about our situation and why we
want to deploy Grizzly.

Our production environment looks like this:

-Everything is Linux.
-2 storage servers, EMC (SATA disks) and HP (SAS disks), using iSCSI
exporting many LUNs to the dom0.
-10 dom0 running between 15 to 25 VMs each with XEN.
-Every dom0 mounts around 8 500Gbytes LUNs with ocfs2 where the small VMs are.
-Some special VMs have their own LUNs because of the space they need,
when a VM needs more than 100Gbytes we create a dedicated LUN for it.
-Having a clustered file system (ocfs2) let us use xen live-migration
for the small VMs.
-We have around 200 VMs running, and is getting a bit complicated to
manage with the actual infrastructure.

Right now we are working on moving to Openstack (Grizzly) so this is
what we have (this is a testing environment):

-1 controller node with HAproxy for API balancing, MySQL, memcached,
rabbitMQ and quantum server. This controller won't be the only one on
the final deployment.
-1 compute node. Here we run most of the APIs and the nova services.
-1 cinder server for block storage, using multibackend. We've defined
two backends one for each storage server. This server has 4 1Gbit
NICs, two of them are bond0 connected to the cloud network, and the
other 2 are bond1 connected to the SAN.

As you know, ephimeral disks are saved in /var/lib/nova/instances so
if we wanted to use live migration we should run ocfs2 to share this
directory between the compute nodes (which is kind of what we have
right now in production). BUT we can only use 1 LUN to mount on this
directory, this way we should create a huge one (more than 2 Tbytes)
to hold all the VMs, which may lead to performance problems.

We could also use cinder volumes for the VMs, maybe spliting things
like: system file disk (ephimeral) and application files disk (cinder
volumes). This way we'd have hundreds of iSCSI volumes managed by
cinder (LVM+EMC and LVM+HP) around one for each VM. What do you think
about this solutions performance???

Compute node <-> iSCSI <-> Cinder server (LVM) <-> iSCSI <-> Storage Servers

Any comment/experience/suggestion/anything will be more than helpful! Thanks

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Pavlik Salles Juan José