Xen users - Aug 2008 - first time w/ XEN - Looking for some advise

Hi,

I have a server that I can use to work with XEN on. It''s a dell  
poweredge 1950, 64 bit 2.6ghz, single quad core cpu. Has about 2 GB of  
ram, and 1XX GB in a raid 5 setup.

I''ve been reading and trying to gather what is the best way to set  
this up. My questions....

1.) What''s the best say to setup the Raid for this? Is Raid 5 Ideal?  
(I have a 4 disk setup - currently 3 disks are part of the raid 5 w/ 1  
being a hotspare).

2.) What is the communities take on using CentOS 5 - x86_64 for the  
base OS?  Is there anything that the base install really needs? I  
generally try to shy away from installing Gnome/KDE/X on my servers as  
to reclaim some resources, but the idea of having a GUI to install  
this stuff would make things more simple I would think.

3.) I''ve read about having a separate LVM for the virtual machines and
one for your OS. Is this really the best way? I understand the reason  
for the LVM, so you can add more storage as you need it, but do you  
really need two?

4.) My last question for now is , if your running an x86_64 system,  
are you limited to running only 64 bit OS''s or like any machine you  
can still install x86 with no problems?

Thank you for any help,

Charlie

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Hi,

On Wed, Aug 27, 2008 at 2:09 PM, Charlie Reddington
<charlie.reddington@gmail.com> wrote:
> Hi,
>
> I have a server that I can use to work with XEN on. It''s a dell
poweredge
> 1950, 64 bit 2.6ghz, single quad core cpu. Has about 2 GB of ram, and 1XX
GB
> in a raid 5 setup.
>
> I''ve been reading and trying to gather what is the best way to set
this up.
> My questions....
>
I''ll take a shot at a couple of them, that I have personal experience
with.

I''ll leave the other ones for others to give their insights.
> 1.) What''s the best say to setup the Raid for this? Is Raid 5
Ideal? (I have
> a 4 disk setup - currently 3 disks are part of the raid 5 w/ 1 being a
> hotspare).
>
Raid Levels often depend on workload and also the nature of the data being
protected. Others can probably give more insight, but I am sure you can also
find Raid advices all over the internet.
> 2.) What is the communities take on using CentOS 5 - x86_64 for the base
OS?
>  Is there anything that the base install really needs? I generally try to
> shy away from installing Gnome/KDE/X on my servers as to reclaim some
> resources, but the idea of having a GUI to install this stuff would make
> things more simple I would think.
>
CentOS 5 x86_64 has worked well in my personal experience. Typically it is
recommended to use the Virt-Manager GUI, but it is not necessary to do so.
You can get away with all command line if no X is desired. You even still have
remote management options through virt-manager remotely, web-based solutions,
and other client based solutions.
> 3.) I''ve read about having a separate LVM for the virtual machines
and one
> for your OS. Is this really the best way? I understand the reason for the
> LVM, so you can add more storage as you need it, but do you really need
two?
>
You don''t have to, it is often recommended for the flexibility of LVM,
but this can
also be a matter of personal preference depending on your performance,
flexibility,
etc. needs.
> 4.) My last question for now is , if your running an x86_64 system, are you
> limited to running only 64 bit OS''s or like any machine you can
still
> install x86 with no problems?
>
No, you can run both 64 bit and 32 bit systems.

Hope that helps.
> Thank you for any help,
>
Welcome and I am sure that you will get other useful answers from others in the
community.


Cheers,
Todd

-- 
Todd Deshane
http://todddeshane.net
check out our book: http://runningxen.com

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Hi Charlie,

A few suggestions based on my experiences:

On Wed, 2008-08-27 at 13:09 -0500, Charlie Reddington
wrote:
> 1.) What''s the best say to setup the Raid for this? Is Raid 5
Ideal?
> (I have a 4 disk setup - currently 3 disks are part of the raid 5 w/ 1  
> being a hotspare).
For just 3 disks, RAID-5 should be OK. A year ago I brought a server up
that had 8x 250 GB drives and made the mistake of putting them into one
big RAID-5 array. The performance hit was noticed after 10 guests were
brought up that did a substantial amount of I/O.

The server had 16 GB of RAM, so our hope was to pack it as full as we
could.. however we ended up splitting the drives up into 4x RAID1 arrays
as it became obvious that any more guests would just make things really
sluggish.
> 2.) What is the communities take on using CentOS 5 - x86_64 for the  
> base OS?  Is there anything that the base install really needs? I  
> generally try to shy away from installing Gnome/KDE/X on my servers as  
> to reclaim some resources, but the idea of having a GUI to install  
> this stuff would make things more simple I would think.
Many people are very happy with CentOS 5. Redhat is doing quite a lot of
work at simplifying tools (for instance, I can''t wait to see Ovirt work
with Xen and appear in RHEL).

I personally like Ubuntu or Debian, but only because I am a big fan of
the apt package manager and find networking a little easier to manage on
Debian based distributions.

You might find CentOS a little easier to manage.
> 3.) I''ve read about having a separate LVM for the virtual machines
and
> one for your OS. Is this really the best way? I understand the reason  
> for the LVM, so you can add more storage as you need it, but do you  
> really need two?
Yes, this is the best way go to, for flexibility and performance. If
possible, set up the RAID so that you can have a physical volume just
for guests.

Using LVM to manage dom-0 is really just a matter of preference.. having
the guest file systems under LVM is whats most important.
 
Cheers,
--Tim

-- 
Monkey + Typewriter = Echoreply ( http://echoreply.us )


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(Accidentally sent this offlist, resending)

1) I recommend never, ever using RAID5.  There are plenty of articles around on
why it is a terrible standard, so I won''t say too much more on this. 
Were I you, I would use RAID-0+1 (Two RAID-0s with RAID-1 across them) or
RAID-10 (RAID-1s with a RAID-0 across them).  (RAID-10 is preferred).
http://decipherinfosys.wordpress.com/2008/01/15/difference-between-raid-01-vs-raid-10/

2) I personally prefer ubuntu for the Dom0.  The repository stays pretty up to
date.  Oh, and Dom0 should always be x64.

3) Well, the best way is actually to have remote storage, but if you''re
going to use local disks, it is a good idea to have separate LVMs.  You
don''t need two, but it''s more logical this way.

4) Nope, you are not limited to 64-bit guests.  Although there are very few
reasons to use 32bit OSs these days.

Good luck!

Thank you,
Nathan Eisenberg
Sr. Systems Administrator
Atlas Networks, LLC

-----Original Message-----
From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Charlie Reddington
Sent: Wednesday, August 27, 2008 11:10 AM
To: xen-users@lists.xensource.com
Subject: [Xen-users] first time w/ XEN - Looking for some advise

Hi,

I have a server that I can use to work with XEN on. It''s a dell  
poweredge 1950, 64 bit 2.6ghz, single quad core cpu. Has about 2 GB of  
ram, and 1XX GB in a raid 5 setup.

I''ve been reading and trying to gather what is the best way to set  
this up. My questions....

1.) What''s the best say to setup the Raid for this? Is Raid 5 Ideal?  
(I have a 4 disk setup - currently 3 disks are part of the raid 5 w/ 1  
being a hotspare).

2.) What is the communities take on using CentOS 5 - x86_64 for the  
base OS?  Is there anything that the base install really needs? I  
generally try to shy away from installing Gnome/KDE/X on my servers as  
to reclaim some resources, but the idea of having a GUI to install  
this stuff would make things more simple I would think.

3.) I''ve read about having a separate LVM for the virtual machines and
one for your OS. Is this really the best way? I understand the reason  
for the LVM, so you can add more storage as you need it, but do you  
really need two?

4.) My last question for now is , if your running an x86_64 system,  
are you limited to running only 64 bit OS''s or like any machine you  
can still install x86 with no problems?

Thank you for any help,

Charlie

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