Re: [Xen-users] Memory and other settings for xen server, help needed....

[Ernst Bachmann <e.bachmann@xxxxxxxx>]

On Tuesday 27 September 2005 15:43, Robin van Leeuwen wrote:
> Hi all,
>
> i have a question. I'm going to setup a Xen server for a client.
> It's going to serve about 25 clients.
>
> It's a Athlon 64 3200+, which currently runs Debian i386-stable and xen
> 2.0.7
> until Xen 3.0 is stable enough, and then i'm gonna replace it with
> Debian amd64-stable and Xen 3.0.
>
> The Xen dom's consists of:
>
> Samba , file printer sharing most active all 25 users all the time
>               network io is a lot.
> Mail      25 users, + webmail + clamav + spamassassin + amavis
> Proxy    squid + squidguard + willowbark (uvscan, which cooperates with
> the www
>              who does the actual scanning)
> WWW   www server for about 25 concurrent users, who access the some of the
>              samba files. Not very IO heavy but some disk IO is involved.
> dom0

First thing I'd test here would be if you can get a reliable, high throughput 
network connection to the domU supposed to run samba.

From my experience with xen-2, I wouldn't run network intense apps in domU. 
Haven't tested samba, but a nfs-server inside domU was nearly unusable.

Next thing: the www server is going to access the same files that are shared 
by samba? How did you plan to share that filesystem between the two domUs? 
smb-mount it inside the WWW domU? Might be ok if there's only little load on 
it, otherwise merge the two domains (would also make it easier if your www 
app should share authentication data with samba).

Another thing you might want to consider: sharing your files from domU wastes 
quite some memory, as they'll be cached twice:
the dom0 caches the blockdevice, and domU caches it again.

> Full spec's at bottom:
>
> The server is a (overkill but it's going to last at least 5 to 7 years) :
> AMD athlon 64 3200+
> 2 G internal DDR 400 Mhz
> Sata drive (hdparm -Tt gives 1549/65.33 mb/sec)
> radeon 9600 don't know how much mem, but who care's it won't be running X
> Marvell Yukon Gigabit Lan onboard.
>
> How should i divide the memory for the dom's , what about swap?
> i was thinking:
>
> DOM    MEM    SWAP
> dom0   512      750
> samba 768      250
> www   256      100
> proxy   256      100
> mail   256      100
>

Well, the swapspaces here are quite low, and maybe too much memory for dom0, 
if it does nothing else than manage the domUs. Maybe give each domain at 
least 512MB Swap.

> Any other suggestions are welcome....
> any other info needed?
> any tuning tips?
>
> kind regards and thanks in advcance.

with xen-2, I'd run the setup as follows:
dom0 1GB Ram, 2GB SWAP, running samba and www
proxy 512MB, 1GB Swap
mail 512MB, 1GB Swap.

If you can get reliable networking, maybe:
dom0 256MB, 512MB swap
samba 1GB/2GB (samba+www)
rest divided among mail and proxy

/Ernst

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