Total ram not recognized

Submitted by dragona on Wed, 05/30/2012 - 11:59

Hi, I'm using Cloudmin PRO on CentOS 5.8 For a bug (xen_net: Memory squeeze in netback driver) in the kernel we apply this solutions:

https://bugzilla.redhat.com/show_bug.cgi?id=454285

  1. Edit /etc/grub.conf using your favorite editor. In the "kernel /versionnumberhere" line add the following to the end of the line: dom0_mem=512M An example would look like: kernel /xen.gz-2.6.18-128.1.10.el5 dom0_mem=512M
  2. Edit /etc/xen/xend-config.sxp and change the following: (dom0-min-mem 256) to: (dom0-min-mem=0)
  3. Lastly, reboot your dom0 device. This will completely fix the memory squeeze issue.

Unfortunately with this configuration Cloudmin is unable to see the correct total amount of RAM and I'm unable to create new VM:

Failed to create system : Host system server.cloud.lan cannot be used : An extra 245.19 MB free RAM is needed to create this system

but the RAM is available on the system:

[root@server ~]# xm list Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 512 2 r----- 368.5 [root@scbs-130 ~]# xm dmesg | grep RAM (XEN) Xen-e820 RAM map: (XEN) System RAM: 16342MB (16735100kB) (XEN) Scrubbing Free RAM: ...........................................................................................................................................................done. [root@server ~]#

How can these problem solved?

Status: 
Closed (fixed)

Comments

Submitted by JamieCameron on Wed, 05/30/2012 - 13:25

If you select the host system from the left menu in Cloudmin and click "Edit System", then expand the "Detailed system status" category, what does it show in the "Real memory used for hosting" field?

Submitted by dragona on Thu, 05/31/2012 - 11:08

Hi, for example, on this server we have 14 GB of RAM, without the fix the server report:

Real memory used
520.26 MB out of 13.30 GB

but when I enable the fix and reboot:

Real memory used
254.70 MB out of 512 MB

so the system really see only 512MB of ram.

Cloudmin should be read the RAM from xm dmesg.

Submitted by JamieCameron on Thu, 05/31/2012 - 12:59

Could you post the output from xm info and xm list on your system?

Also, what is the path to your GRuB configuration file, and what does it contain? Cloudmin looks at /boot/grub/menu.lst for the dom0_mem= directive, but GRuB is using a different path that will fail..

Submitted by dragona on Fri, 06/01/2012 - 04:27

xm info:

xm info

host : server release : 2.6.18-308.4.1.el5xen version : #1 SMP Tue Apr 17 17:49:15 EDT 2012 machine : x86_64 nr_cpus : 2 nr_nodes : 1 sockets_per_node : 1 cores_per_socket : 2 threads_per_core : 1 cpu_mhz : 2794 hw_caps : 178bfbff:efd3fbff:00000000:00000110:00802009:00000000:000037ff total_memory : 16342 free_memory : 13460 node_to_cpu : node0:0-1 xen_major : 3 xen_minor : 1 xen_extra : .2-308.4.1.el5 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_pagesize : 4096 platform_params : virt_start=0xffff800000000000 xen_changeset : unavailable cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-52) cc_compile_by : mockbuild cc_compile_domain : centos.org cc_compile_date : Tue Apr 17 17:00:09 EDT 2012 xend_config_format : 2

xm list

Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 513 2 r----- 757.5 cs5-64-template 22 512 1 -b---- 4.3 cs6-64-template 21 512 1 -b---- 4.6 deb-5-template 19 512 1 -b---- 4.1 deb-6-template 20 509 1 -b---- 3.7

cat /boot/grub/menu.lst grub.conf generated by anaconda

#

Note that you do not have to rerun grub after making changes to this file NOTICE: You have a /boot partition. This means that all kernel and initrd paths are relative to /boot/, eg. root (hd0,0) kernel /vmlinuz-version ro root=/dev/md1 initrd /initrd-version.img boot=/dev/md0

default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title CentOS (2.6.18-308.4.1.el5xen) root (hd0,0) kernel /xen.gz-2.6.18-308.4.1.el5 dom0_mem=512M module /vmlinuz-2.6.18-308.4.1.el5xen ro root=/dev/md1 module /initrd-2.6.18-308.4.1.el5xen.img title CentOS (2.6.18-308.4.1.el5) root (hd0,0) kernel /vmlinuz-2.6.18-308.4.1.el5 ro root=/dev/md1 initrd /initrd-2.6.18-308.4.1.el5.img

I think that the problem occurs only when creating the first virtualmachine. I made this test:

Cloudmin PRO without VM and with the fix: - I get the error of not enough RAM.

Cloudmin PRO without VM and without the fix: - All works fine, I create mi first VM.

Now I apply the fix and reboot, can be created new VM.

I hope that this information can be helpfull. Bye

Submitted by JamieCameron on Sat, 06/02/2012 - 05:54

Ok, I think I see now .. so did the problem happen after you modified menu.lst, but went away when you rebooted? Because only on a reboot is the dom0_mem setting in menu.lst actually applied.

Submitted by dragona on Mon, 06/04/2012 - 03:25

Thanks Jamie, the problem cloud be this. Please verify.