[Xen-users] Maximum number of VMs per xen server

[moftah moftah <mofta7y@xxxxxxxxx>]

Hi,

It looks like I am having problems when I create more than 100 VM in
one xen node.

up to 60 VMs there is zero problems and between 60 and 100 problems start

more than 100 the node becomes unstable.

The node has tons of memory (more than 30 GB free)
also the node has 16 cores so the processor isnt the issue here.
is there any limitation in xen that prevent the system from serving
more than 100 VMs ?

the symptoms are that
1- xm command become ultra slow and we are forced to restart the xend
demon regularly (xm create could take 5-20 min).
2- if we restart the node for any reason booting up all the VMs in
/etc/xen/auto will take 4 hours or more if we didnt restart the xend
demon in the middle.
3- the xend demon restart takes between 30 min up to 120 min.
4- after xend restart xm command bocomes fast for a while and start
slowing again as we issue more m commands

Dom-0 memory is 2 GB (i tried with 3 GB with no improvement at all)

xm info result
xm info
host                   : localhost.localdomain
release                : 2.6.32.18
version                : #1 SMP Wed Aug 25 11:17:42 EDT 2010
machine                : x86_64
nr_cpus                : 24
nr_nodes               : 4
cores_per_socket       : 12
threads_per_core       : 1
cpu_mhz                : 2100
hw_caps                :
178bf3ff:efd3fbff:00000000:00001310:00802001:00000000:000837ff:00000000
virt_caps              : hvm
total_memory           : 131070
free_memory            : 112496
node_to_cpu            : node0:0-5
                         node1:6-11
                         node2:18-23
                         node3:12-17
node_to_memory         : node0:20114
                         node1:32671
                         node2:29599
                         node3:30110
node_to_dma32_mem      : node0:3514
                         node1:0
                         node2:0
                         node3:0
max_node_id            : 3
xen_major              : 4
xen_minor              : 0
xen_extra              : .1-rc5
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : Mon Aug 02 11:18:11 2010 +0100 21294:f200573325ba
xen_commandline        : dom0_mem=12048M loglvl=all guest_loglvl=all
console=tty0 console=com2 com2=57600,8n1
cc_compiler            : gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
cc_compile_by          : root
cc_compile_domain      : localdomain
cc_compile_date        : Sat Aug 21 23:10:21 EDT 2010
xend_config_format     : 4


any help will be appreciated

Thanks

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