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Re: [Xen-users] Re: I need advice about xen project

To: christopher andrews <khris4@xxxxxxxxx>
Subject: Re: [Xen-users] Re: I need advice about xen project
From: Aleix Dorca <adorca@xxxxxx>
Date: Mon, 24 Aug 2009 08:15:44 +0200
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I don't know if there's a best way to do it. :-)

The way I did it is: I set up three partitions on 2950 servers. 1 for the OS, 1 for swap, and 1 for drbd (in my case /dev/sda3). This on both servers replicating. Once drbd configured I use LVM on top of it, creating "logical volumes" as needed.

I can snapshot any LV any time and all actions are replicated on the other drbd machine. There's plenty of tutorials dealing with this particular setup. Others, depending on their necessities prefer to have drbd on top of LVM... it also works...


El 24/08/2009, a las 6:52, christopher andrews escribió:

Hey Aleix,

What would be the best way to setup drdb with lvm and still be able to take
lvm snapshoot for backups.

On 8/23/09 9:38 PM, "Aleix Dorca" <adorca@xxxxxx> wrote:

Hi Peter,

sorry to tell you I've never run into performance problems that lead
me to run sar and check steal percentages. Also, I'd have to say that
my VMs don't work to hard most of the time... maybe this helps avoid

The VMs run everything from Active Directory, Exchange, MSSQL (on
Windows 2003 HVM), mysql, apache, tomcat, squid... you name it.


El 23/08/2009, a las 21:34, Peter Booth escribió:


For the servers running over ten domU, have you seen any issues with
unexpected latencies or domU sar showing %steal above 1?
Are any of these domU running web services or web applications?

Sent from my iPhone

On Aug 23, 2009, at 3:14 PM, Aleix Dorca <adorca@xxxxxx> wrote:

Hi Christopher,

no, I don't limit to 4 the domU's on my Xen machines, I have plenty
of servers to spare. I have some servers running 10-12 domU's while
others only run 1-2. Some none, I have them just in case... or for
when new domU's needed. I have not run out of processing power but
I have of RAM. If I had to recommend something that'd be: GET

As for drbd, yes, I'm running an active/passive setup. You could
say a machine is always misused, it's true, but I have an 'on-line'
backup just in case. You could always use an active/active setup
with a cluster aware file system. I tried it but I really didn't
need it.

Hope it helps,


En/na christopher andrews ha escrit:
Hey Aleix,
I notice here that you have 12 dell server running xen for your
domU's, so
does this mean your limit to 4 vm per dom0? This going out the
fact that you
have 30 to 40 domU's running in total from your first e-mail. Also
I see
that you using drbd for you iscsi san on the dell 2950's, I'm also
about using this setup but I'm wonder are they 2950 running
passive active
mode because I believe that drdb can only have one device
accessing the
virtual disk interface at a time.

Thank You,

On 8/23/09 8:08 AM, "Aleix Dorca" <adorca@xxxxxx> wrote:


I need help with a production system that I would like to design
out a my job. I was thinking about buy two server with 16 each
and 8
processor and have both server connect to two dell 2850 server
raid 6
and 3x 300 ultra 320 hard drives. Both dell 2850’s that are being
used a
nas server will be connected to the two new server through
Ethernet. I wonder if this a bad Idea?

Hi Christopher,

the setup you talk about is more or less the same I'm using. I've
using it in a production environment for about a year now without a
single problem. Here's my setup:

12 Dell 1950 Servers with 8 Cores and 4 to 16 Gb (depending on the
4 Dell 2950 Servers with 5 450Gb disks on RAID 5 acting as a SAN
iscsi (2TB aprox each).

The SAN servers are paired and replicated using drbd.

As said no problems running xen 3.1 on Ubuntu and Debian DomU, and
running Debian and CentOS as domU.

All network connections are 1 Gb. I have about 30~40 domU.

Hope it helps,

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