PE1955 + RHEL5 best practices/documentation

[Harald_Jensas at Dell.com]

> -----Original Message-----
> From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-
> bounces at dell.com] On Behalf Of Matthew Crocker
> Sent: 01 January 2008 17:44
> To: linux-poweredge-Lists
> Subject: PE1955 + RHEL5 best practices/documentation
> 
> 
> Hello,
> 
>   I just racked my shiny new Dell Blade chassis with 10 PE1955s (2 x
> quad-core Xeon, 8 Gb RAM, 4 1Gb Ethernet).  The chassis has 4 Dell
> PowerConnect  switches.  I also have a 4.5 TB Dell MD3000i SAN array.
> All of the blades will run RHEL5 with Xen.
> Gold 4 hour support on the whole deal :)
> 
> So, basically I have 10 systems, each with 4 GigE connections, 4 16
> port GigE switches, 1 GigE per server per switch.  I'd like to make
> this setup bullet proof,  I'm planning on 2 GigE switches for iSCSI
> to the MD3000i and 2 for data.    The Data switch will need to support
> about 5 802.1q VLANs (public, private, NFS, management, ...)
> 
> With 2 switches, 2 IP subnets connecting each blade to the M3000i can
> I load balance the traffic and get 2 GigE between the blade and the
> MD3000i?  4 GigE between the MD3000i and the chassis combined?

Yes. There is MultiPath I/O Software included on the MD3000i Resource CD.

Documentation is available here:
http://support.euro.dell.com/support/edocs/systems/md3000i/en/IG/PDF/IGbk0HR.pdf

> 
> Is there a way I can bond 2 GigEs into a 2 gigabit EtherChannel across
> two PowerConnect switches?

You will not be able to create a 802.3ad LAG team containing NICs that is connected to different switches.
However it might be possible to create a team that will "load balance" outbound traffic, and possibly even failover nicely by broadcasting a reverse arp if link failure is deteceted.

> 
> Is there a way I can link the switches together inside the chassis or
> do I need to run an external cross over cable between them?

No you will have to use a cross over or link them together via another external switch.

>
> The MD3000i has a limit of 16 hosts.  Does that count as real physical
> servers or virtual servers?  i.e., can I run 4 Xen instances per blade
> and have them all run an iSCSI initiator?  Would that be 10 hosts or
> 40 from the MD3000i point of view?

That would be 40 hosts from the MD3000i's point of view. 
It is possible to install the iSCSI initiator in dom0 of each blade and then connect the LUNs to the VMs via dom0. It will put some more load on each physical server but you will be able to let 40 VMs use the MD3000i Storage capacity.



Regards
Harald Jensås