Xen users - Jun 2006 - newbie questions re. setting up a 2-node HA cluster

Hi Folks,

Following up a bit on the GFS vs. EVMS thread from last month...

Hi Folks,

I''m about to migrate from a dedicated RH9 server (mostly email, list 
serving, web serving) to a couple of new machines that I''ll be
deploying
  in a colocation arrangement - with a lot more control over configuration.

My current box is pretty basic - using RAID-1 and nightly backups to 
provide a measure of reliability.  I''m planning on taking the 
opportunity of deploying new machines to build a more robust site.

As I explore the options, I''m running into more questions than answers,
so I''d very much appreciate any guidance that anyone can offer on the 
following (and on any other topics you think are relevant).

My basic idea is to run two boxes - one as primary, one configured for 
automatic failover.  Beyond that I''m thinking of running a few virtual 
servers for staging/experimentation purposes.

The hardware I have available are fairly high-end i86 boxes, 2Gig each, 
with 4 400Meg SATA drives in each, and dual gigE nics.

On to questions:

1. I''m looking to provide a highly reliable underlying storage system. 
My thoughts are to use DRBD to mirror across the two boxes, but I''d
also
like to mirror drives, in pairs, on each box.  Any suggestions regarding 
how to md or some other software raid with DRBD (or ENBD)?

2. The next layer up: any suggestions regarding LVM vs. EVMS for 
managing all the disk space, in combination with the lower level mirroring?

3. I''m also thinking of mirroring to a remote backup site.  Any 
suggestions regarding adding network mirroring into the mix?  Or am I 
better off using something like CODA at the file system level?

4. I''d like to explore using one of the BSDs.  I assume right now my 
choice is Xen 2 if I want to run a BSD Dom0 (and I''m not sure that any 
of the above mirroring/filesystem approaches work with BSD).  Am I 
correct that I can run BSD DomUs with the current release of Xen 3?  Any 
thoughts/suggestions here?

5. Any suggestions regarding running databases on all of this (mostly to 
support my list manager, sympa)?

6. Any suggestions regarding management tools for this motley assemblage 
of stuff?

7. Am I going to take tremendous performance hits from all of this?

8. Am I crazy for considering all of this? (Maybe heresy on this list, 
but am I better off considering an all Linux/vserver, or all BSD/jails 
approach?)

Thanks very much, in advance, for any suggestions.

Miles Fidelman

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