Re: [Xen-users] Please comment on proposed configuration

["Dirk H. Schulz" <dirk.schulz@xxxxxxxxxxxxx>]

John S Little schrieb:

> Hello all,
>
> Having built 1 test Xen machine and followed this list now for several 
> weeks I hope that I have some understanding of  what I can/can't 
> should/shouldn't do.
> Hardware configuration:
> I have a hardware configuration consisting of a Sun Fire V20z, dual proc 
> AMD 272 and 4gb of ram.  The dom0 is SuSE 9.3, patched with the "in the 
> box" version of Xen 2.0.5.  The machine has two Broadcom Gb nics, an added 
> Intel dual port Gb nic card, connected to Gb switches.  Storage consists 
> of a single Qlogic QLA2342-E-SP dual port connected to a McData switch 
> using an EMC CX600 for storage.  The Qlogic card will be hidden from dom0.
> An overview of what I want to do:
> Provide  domU Samba file servers for various departments.  Each file 
> server would carry about 50 users.  Heavier use departments would be 
> paired with lighter use departments.  Each domU would be configured to use 
> 512Mb of memory (dom0 is configured with 128Mb).   This would allow me to 
> have 7 domU and about 350 users.  The domUs are configured with SLES9 sp1.
> A future consideration would be to add heartbeat into the mix and create a 
> failover server using the shared storage.
> 1.  Is this to much of a load for Xen file serving? Conversely could more 
> users be added than this?  I realize that this is somewhat subjective and 
> would depend on utilization rates but I need to start somewhere :-)
>  
There is nothing to add to that. You simply have to measure.

> 2.  Are the two extra nic ports provided by the Intel card going to be 
> useful?  I read just today that the domU machines are only going to see 
> one NIC?
>  
The NICs in the domU are virtual (as long as you do not set up 
privileged domUs and move real PCI devices to them). You can have as 
many NICs in domU as you want (there is a maniac called Marcus who uses 
12 NICs in one of his setups ... look at the thread "ideallistic firewal 
design" in the archives).
> 3.  Would the Intel slot be better served by using a 2nd Qogic hba?
>  
Depends on what you want to achieve. Having a second way to the storage 
system is good as long as your SAN can be configured to use it.
> 4. Since each domU is running the same server (SLES 9) do (can?) I use the 
> same kernel?  My guess is that the best solution is to use separate 
> kernels for each domU else if one crashes they all crash..
>  
No, you can use the same kernel because every domU starts its own 
instance of this kernel. If one of them crashes the others ought to go on.
> 5.  Since this is a production server in a hospital, when servers don't 
> work (even file servers) things get critical in a hurry.  This is one of 
> the reasons I am hesitant to consider Xen 3.  Would Xen 3 be better suited 
> for this environment? If so should I wait on it or could I deploy it now?
>  
I tried Xen3 2 oder 3 weeks ago and was disappointed of stability (sorry 
to the developpers) - I would not recommend it in a production 
environment. As long as you do not want to use 64 Bit 
Applications/Systems or hardware based virtualization (VT), I do not see 
a reason to wait for xen 3.
> One last question-When I compile a kernel for use with domU do I compile 
> it inside domU or inside dom0?
>  
Since you need a ready kernel to start domU you cannot compile it inside 
domU? Or do I misunderstand your question?
I use xen sources as a starting point and always compile in dom0 since 
all the kernels are stored in dom0 anyway.
Dirk

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