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OS:Xen Cloud Platform 1.1 (XCP) modified centos, and xen server 5.0 running on intel i5

free -m

               total       used        free     shared    buffers    cached
       Mem:     309         136        172        0         1          17
-/+ buffers/cache:         117         191
Swap:           511          7         504

df -h

none                  380M     0  380M   0% /dev/shm

cat /proc/meminfo

MemTotal:         316416 kB
MemFree:           79024 kB
Buffers:            5444 kB
Cached:            79304 kB
SwapCached:            0 kB
Active:            48020 kB
Inactive:          64092 kB
Active(anon):      30572 kB
Inactive(anon):     1624 kB
Active(file):      17448 kB
Inactive(file):    62468 kB
Unevictable:        6436 kB
Mlocked:            6436 kB
HighTotal:             0 kB
HighFree:              0 kB
LowTotal:         316416 kB
LowFree:           79024 kB
SwapTotal:        524280 kB
SwapFree:         524280 kB
Dirty:               172 kB
Writeback:             0 kB
AnonPages:         33876 kB
Mapped:            17864 kB
Shmem:               124 kB
Slab:              17100 kB
SReclaimable:       8276 kB
SUnreclaim:         8824 kB
KernelStack:        1464 kB
PageTables:            0 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:      682488 kB
Committed_AS:     647196 kB
VmallocTotal:     245752 kB
VmallocUsed:        4576 kB
VmallocChunk:     237148 kB
DirectMap4k:      754492 kB
DirectMap2M:           0 kB**

top output

Mem:    316416k total,   237992k used,    78424k free,     5636k buffers
Swap:   524280k total,        0k used,   524280k free,    79404k cached

top sorted based on ram (shift+m)

top - 14:59:20 up 29 min,  1 user,  load average: 0.00, 0.00, 0.00
Tasks: 113 total,   1 running, 112 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si,
0.0%st
Mem:    316416k total,   238008k used,    78408k free,     5708k
buffers
Swap:   524280k total,        0k used,   524280k free,    79440k
cached
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 5942 root      17  -3  179m  12m 5492 S  0.3  4.2   0:05.72 xapi
 6964 root      20   0 11776 7672 2856 S  0.3  2.4   0:00.87 python
 5939 root      17  -3 21524 6092 2880 S  0.0  1.9   0:00.00 xapi
 6700 root      20   0 11768 5028 1644 S  0.0  1.6   0:00.16 python
 5740 ntp       20   0  4496 4496 3488 S  0.0  1.4   0:00.05 ntpd
 6398 root      20   0 27772 4052 1020 S  0.0  1.3   0:00.01 snapwatchd
 5634 root      20   0  170m 3620 2664 S  0.0  1.1   0:00.02 lwregd
 5527 root      RT   0  3432 3432 2708 S  0.0  1.1   0:00.04 multipathd
 7909 root      20   0 10168 2824 2268 S  0.0  0.9   0:00.03 sshd
 6128 root      20   0 29608 2792 1540 S  0.0  0.9   0:00.03 mpathalert
 7921 root      20   0  5152 2024 1268 S  0.0  0.6   0:00.05 bash
 5632 root      20   0  173m 1576 1036 S  0.0  0.5   0:00.00 lwsmd
 5241 root      10 -10  5988 1504  928 S  0.0  0.5   0:00.30 ovs-vswitchd
 5804 root      20   0  2992 1472  564 S  0.0  0.5   0:00.09 fe
 5909 root      20   0 11600 1452  912 S  0.0  0.5   0:00.04 squeezed
 5228 root      10 -10  5448 1440 1052 S  0.0  0.5   0:00.08 ovsdb-server
 5858 root      20   0  5360 1304  780 S  0.0  0.4   0:00.03 xenstored
 5831 root      20   0 12964 1212  756 S  0.0  0.4   0:00.00 v6d
 6552 root      20   0  5384 1108  572 S  0.0  0.4   0:00.00 crond
 8122 root      20   0  2404 1104  836 R  0.3  0.3   0:00.41 top
 6499 root      20   0  7180 1068  664 S  0.0  0.3   0:00.00 sshd
 5834 root      20   0 21112 1064  604 S  0.0  0.3   0:00.36 v6d
 6968 root      20   0  4492 1044  672 S  0.0  0.3   0:00.00 vncterm
 6969 root      20   0  2544 1044  912 S  0.0  0.3   0:00.00 dom0term.sh
 5240 root      10 -10  5880  832  272 S  0.0  0.3   0:00.28 ovs-vswitchd
 1527 root      16  -4  2364  744  396 S  0.0  0.2   0:01.24 udevd
    1 root      20   0  2156  664  564 S  0.0  0.2   0:00.21 init
 5563 rpc       20   0  1904  644  548 S  0.0  0.2   0:00.00 portmap
 6038 root      17  -3  5208  632  272 S  0.0  0.2   0:00.00 stunnel
 5376 root      20   0  1808  616  516 S  0.0  0.2   0:00.01 syslogd
 5227 root      10 -10  5444  556  280 S  0.0  0.2   0:00.27 ovsdb-server
 5861 root      20   0 10392  548  436 S  0.0  0.2   0:00.00 xenconsoled
 5869 root      20   0  3072  476  256 D  0.0  0.2   0:00.51 cdrommon
 6967 root      20   0  1752  472  404 S  0.0  0.1   0:00.00 agetty
 6965 root      20   0  1740  452  388 S  0.0  0.1   0:00.00 mingetty

on BIOS 4 GB of installed RAM is showing.In the same machine earlier ubuntu 12.04 was running with out showing any RAM problem.

update:

in the xsconsole(xen console)>Hardware and BIOS Information>System memory>

total memory 4096 MB

Populated memory sockets 2

Total memory Sockets 4

share|improve this question
    
Are you checking this on a VM or on the hypervisor? Are you sure your BIOS has detected 4GB of RAM? –  Chida Aug 13 '12 at 4:25
    
What's the system? Latest BIOS? On the Xen HCL? –  Chris S Aug 13 '12 at 4:27
    
@Chris S on top output and cat ouput its showing 4Gb but on free -m its showing only 300 mb of total ram. –  ananthan Aug 13 '12 at 4:34
    
@chida checking on the hyperviosr.on top and /proc/meminfo output its showing 4 Gb RAM –  ananthan Aug 13 '12 at 4:35
1  
@ananthan: Hmm? Your top output shows 300 MB RAM as well. –  Janne Pikkarainen Aug 13 '12 at 7:07

1 Answer 1

up vote 1 down vote accepted

dom0 memory is constrained by parameters in the extlinux boot param in/boot/extlinux.conf (look for the dom0_mem). Here in my conf below it is set to 752Mo, and it may vary after installation depending on the whole RAM of the server.

cat /boot/extlinux.conf

...
label xe
# XCP
kernel mboot.c32
append /boot/xen.gz dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M console= vga=mode-0x0311 --- /boot/vmlinuz-2.6-xen root=LABEL=root-nddcwqei ro xencons=hvc console=hvc0 console=tty0 quiet vga=785 splash --- /boot/initrd-2.6-xen.img
...

RAM used by dom0 is not available for virtual machines, it is used for network bridging and physical block device handling, etc.

So it means that you have 4GiB - 300MiB of RAM available for your virtual machines.

share|improve this answer
    
thanks ZVIK...i was not aware of that...thanks alot... –  ananthan Aug 13 '12 at 9:36

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