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

[John S Little <JSLittl@xxxxxxxxxxxxx>]

Dirk

Thank you for your input...
xen-users-bounces@xxxxxxxxxxxxxxxxxxx wrote on 11/01/2005 04:33:15 AM:

> Date: Tue, 01 Nov 2005 10:32:34 +0100
> From: "Dirk H. Schulz" <dirk.schulz@xxxxxxxxxxxxx>
> Subject: Re: [Xen-users] Please comment on proposed configuration
> To: John S Little <JSLittl@xxxxxxxxxxxxx>,
>    xen-users@xxxxxxxxxxxxxxxxxxx
> Message-ID: <43673632.70603@xxxxxxxxxxxxx>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> 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.

Ok good. 

> 
> >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).

Ok I'll have a look at this.


 
> >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.

My SAN supports multipath but I was thinking more of the paths required 
for heartbeat.  I would prefer to have at least 3 paths (2 lan and 1 
serial)
 
> >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.

Ok.

 
> >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.

Does this mean that I shouldn't or can't  use SLES9 64 bit for the OS?  I 
wasn't planning on using hardware based virtualization.

 
> >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.

Doh! ok.  You understood it correctly.  I was thinking, incorrectly of 
course, that you brought up a domU with a stock kernel and then compiled a 
kernel to match.

> 
> Dirk

Thanks for helping me understand this more.

John

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