Only 2GB of 4GB available Dell PowerEdge 860

Submitted by cobolt on Wed, 09/22/2010 - 05:06

This is not directly a cloudlmin problem but it appeared after rebooting with the xen kernel from a fresh install of Debian 5.0 amd64 and cloudmin pro. Any suggestions?

free
             total       used       free     shared    buffers     cached
Mem:       2538496     299684    2238812          0       7380      34328
-/+ buffers/cache:     257976    2280520
Swap:      9896000          0    9896000

uname -a
Linux 2.6.26-1-xen-amd64 #1 SMP Fri Mar 13 21:39:38 UTC 2009 x86_64 GNU/Linux

grub> displaymem
displaymem
 EISA Memory BIOS Interface is present
 Address Map BIOS Interface is present
 Lower memory: 640K, Upper memory (to first chipset hole): 3072K
 [Address Range Descriptor entries immediately follow (values are 64-bit)]
   Usable RAM:  Base Address:  0x0 X 4GB + 0x0,
      Length:   0x0 X 4GB + 0xa0000 bytes
   Reserved:  Base Address:  0x0 X 4GB + 0xa0000,
      Length:   0x0 X 4GB + 0x60000 bytes
   Usable RAM:  Base Address:  0x0 X 4GB + 0x100000,
      Length:   0x0 X 4GB + 0x300000 bytes
Status: 
Active

Comments

Submitted by andreychek on Wed, 09/22/2010 - 09:21

Hmm... did you see all 4GB there when running "free" under a different kernel? I'd be curious to see what free looked like under the original Debian kernel you had been using.

Submitted by JamieCameron on Wed, 09/22/2010 - 12:32

What does your /boot/grub/menu.lst file contain?

Does it reserve any memory for the dom0 ?

Submitted by cobolt on Thu, 09/23/2010 - 04:40 


default         0

timeout         5

color cyan/blue white/blue

title           Xen 3.2-1-amd64 / Debian GNU/Linux, kernel 2.6.26-1-xen-amd64
root            (hd0,0)
kernel          /boot/xen-3.2-1-amd64.gz
module          /boot/vmlinuz-2.6.26-1-xen-amd64 root=/dev/sda1 ro console=tty0
module          /boot/initrd.img-2.6.26-1-xen-amd64

title           Debian GNU/Linux, kernel 2.6.26-2-amd64
root            (hd0,0)
kernel          /boot/vmlinuz-2.6.26-2-amd64 root=/dev/sda1 ro quiet
initrd          /boot/initrd.img-2.6.26-2-amd64

title           Debian GNU/Linux, kernel 2.6.26-2-amd64 (single-user mode)
root            (hd0,0)
kernel          /boot/vmlinuz-2.6.26-2-amd64 root=/dev/sda1 ro single
initrd          /boot/initrd.img-2.6.26-2-amd64

title           Debian GNU/Linux, kernel 2.6.26-1-xen-amd64
root            (hd0,0)
kernel          /boot/vmlinuz-2.6.26-1-xen-amd64 root=/dev/sda1 ro quiet
initrd          /boot/initrd.img-2.6.26-1-xen-amd64

title           Debian GNU/Linux, kernel 2.6.26-1-xen-amd64 (single-user mode)
root            (hd0,0)
kernel          /boot/vmlinuz-2.6.26-1-xen-amd64 root=/dev/sda1 ro single
initrd          /boot/initrd.img-2.6.26-1-xen-amd64

Submitted by JamieCameron on Thu, 09/23/2010 - 11:42

Do you have any Xen instances running on the host when you run free ? Because I am pretty sure that memory allocated to Xen instances disappears from the total for the host systems..

Submitted by cobolt on Sun, 09/26/2010 - 12:55

You are correct.

If I use "xm top" instead of free or top I get the correct memory total. So everything is fine.

Would it make sense to calculate the memory differently or use a different label for the "Cloudmin Information" page where "Real Memory" shows the memory on dom0 not the actual "real" memory?

Maybe add a field for "Physical memory"?

Submitted by JamieCameron on Sun, 09/26/2010 - 14:03

If you check the "Edit System" page for a host system, in the "Detailed system status" section there should be a "Real memory for hosting" bar chart that takes Xen memory usage into account. This can differ quite a lot from the memory shown by the free command, as you can limit the dom0 (Xen host) to a fixed amount of memory via a kernel option.