[Xen-users] Physical memory not fully available to DomU's

[Dennis Storm - Drecomm BV <d.storm@xxxxxxxxxx>]

Hi,

I'm having a weird problem with one of my Xen machines. I have a 96Gb 
ram server, running on Debian 6 with Xen kernel. However, I can only 
assign memory out of a pool of 24GB, the rest is unavailable for 
assignment. When trying to run a new DomU i'm getting the error that 
there isn't enough free ram. However, when I do the math myself I can 
see that there's 22GB of ram in use, which leave 74GB available (minus 
Dom0 minimum limit, which is set at 8GB).
I've tried disabling ballooning, i als saw posts of ram missing due to 
the balloondriver, but nothing in the likes of this volume of missing ram.
Any help would be very much appreciated. Seems a shame to let 74GB go to 
waste. If you need any more info, please let me know!
XM info output:
--------------
host                   : <blotted out>
release                : 2.6.32-5-xen-amd64
version                : #1 SMP Tue Jun 14 12:46:30 UTC 2011
machine                : x86_64
nr_cpus                : 16
nr_nodes               : 2
cores_per_socket       : 4
threads_per_core       : 2
cpu_mhz                : 2400
hw_caps                : 
bfebfbff:2c100800:00000000:00001f40:009ee3fd:00000000:00000001:00000000
virt_caps              : hvm
total_memory           : 98295
free_memory            : 19
node_to_cpu            : node0:0-3,8-11
                         node1:4-7,12-15
node_to_memory         : node0:19
                         node1:0
node_to_dma32_mem      : node0:0
                         node1:0
max_node_id            : 1
xen_major              : 4
xen_minor              : 0
xen_extra              : .1
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          : unavailable
xen_commandline        : placeholder
cc_compiler            : gcc version 4.4.5 (Debian 4.4.5-10)
cc_compile_by          : waldi
cc_compile_domain      : debian.org
cc_compile_date        : Wed Jan 12 14:04:06 UTC 2011
xend_config_format     : 4
--------------

XM List output:
-----------
Name                                        ID   Mem VCPUs      State   
Time(s)
Domain-0                                     0 11257    16     r-----  
24477.0
<hostname blotted out>                      25   256     8     -b----   
4233.8
<hostname blotted out>                      11  1024     8     -b----   
1725.5
<hostname blotted out>                       2  4192     8     r-----  
66563.5
<hostname blotted out>                       3   512    16     -b----  
15330.1
<hostname blotted out>                      17   512    16     -b----   
5249.6
<hostname blotted out>                      18   512    16     -b----  
12292.2
<hostname blotted out>                     19   512     1     -b----   
6620.5
<hostname blotted out>                       8   512    16     -b----   
1554.6
<hostname blotted out>                       9  1024     4     -b----   
1837.1
<hostname blotted out>                      12  1024     4     -b----   
5932.5
<hostname blotted out>                      13  1024    16     -b----  
35491.3
<hostname blotted out>                      22  1024     8     -b----   
5505.7
<hostname blotted out>                      20   512     1     -b----  
15667.6
<hostname blotted out>                      23  2816     8     -b----   
6621.9
<hostname blotted out>                      26   512     1     -b----  
11633.6
<hostname blotted out>                      28   512    16     -b----    
906.9
<hostname blotted out>                      15   512     1     -b----  
17502.6
<hostname blotted out>                      27   256     1     -b----   
3924.0
<hostname blotted out>                       7   512     1     -b----  
12216.5
<hostname blotted out>                       6   512     1     -b----   
9732.1
<hostname blotted out>                      29  2048    16     -b----   
1738.4
<hostname blotted out>                       4   256     8     -b----   
4346.0
<hostname blotted out>                      30  2048     8     -b----   
4066.8
Total ram used for all DomU's: 22624MB
----------------------

Config for DomU (generic for all running DomU's, except ram and core 
assignments)
----------------------

#
#  Kernel + memory size
#
kernel  = '/boot/vmlinuz-2.6.32-5-xen-amd64'
ramdisk = '/boot/initrd.img-2.6.32-5-xen-amd64'

memory  = '2048'
vcpus   =  '8'
extra = 'xencons=tty'

#
#  Disk device(s).
#
root    = '/dev/xvda1 ro'
disk    = [ 'file:/storage/target/disk.img,xvda,w', 
'file:/storage/target/swap.img,xvdb,w' ]
#
#  Hostname
#
name    = '<hostname blotted out>'

#
#  Networking
#
vif  = [ 'ip=<obscured>' ]

#
#  Behaviour
#
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'

--------

xend-config.sxp
--------
(network-script network-bridge)
(vif-script vif-bridge)
(dom0-min-mem 196)
(enable-dom0-ballooning yes)
(total_available_memory 0)
(dom0-cpus 0)
----------

Kind regards,

Dennis Storm - Drecomm BV

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