Wrong real memory

Submitted by farenheitcx on Sat, 11/21/2015 - 15:30

Installed Webmin & Cloudmin on my server but I have this bug with the "Real Memory", the system detect 8GB but Webmin/Cloudmin only show "902.77 MB total / 172.51 MB used"

    System: CentOS release 6.7 (Final)
    Xen Kernel: 3.18.21-16.el6.x86_64
    Webmin Version: 1.770
    Cloudmin Version: 8.3

Here is my cat /proc/meminfo

cat /proc/meminfo
MemTotal:         946628 kB
MemFree:           87316 kB
MemAvailable:     792144 kB
Buffers:           52156 kB
Cached:           627584 kB
SwapCached:        53148 kB
Active:           201904 kB
Inactive:         537236 kB
Active(anon):       1112 kB
Inactive(anon):    58328 kB
Active(file):     200792 kB
Inactive(file):   478908 kB
Unevictable:           4 kB
Mlocked:               4 kB
SwapTotal:       2097148 kB
SwapFree:        2025112 kB
Dirty:                 4 kB
Writeback:             0 kB
AnonPages:          7184 kB
Mapped:            12064 kB
Shmem:                12 kB
Slab:              87240 kB
SReclaimable:      39660 kB
SUnreclaim:        47580 kB
KernelStack:        2112 kB
PageTables:         2392 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     2570460 kB
Committed_AS:     112632 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      101384 kB
VmallocChunk:   34359629944 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:     1048964 kB
DirectMap2M:           0 kB
Status: 
Closed (fixed)

Comments

Submitted by JamieCameron on Sat, 11/21/2015 - 23:15

Is this the memory available in a VM, or on the host system?

Also, if it's on a host, what does the xm info command output?

Submitted by farenheitcx on Sun, 11/22/2015 - 10:24

Is on the host system (Dom0)

Here is my xm info output

host                   : xen1.domain.tld
release                : 3.18.21-16.el6.x86_64
version                : #1 SMP Sat Sep 26 01:24:19 UTC 2015
machine                : x86_64
nr_cpus                : 4
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 2808
hw_caps                : bfebfbff:28100800:00000000:00003b00:0098e3fd:00000000:00000001:00000000
virt_caps              : hvm
total_memory           : 8158
free_memory            : 5979
free_cpus              : 0
xen_major              : 4
xen_minor              : 4
xen_extra              : .3-3.el6
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          : Wed Oct 21 16:18:30 2015 +0100 git:5418e02-dirty
xen_commandline        : dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all
cc_compiler            : gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)
cc_compile_by          : mockbuild
cc_compile_domain      : centos.org
cc_compile_date        : Thu Oct 29 12:18:52 UTC 2015
xend_config_format     : 4

Thanks in advance!

Submitted by JamieCameron on Sun, 11/22/2015 - 20:19

Can you also post the output from :

grep dom0_mem /boot/grub/*

the problem may be that your system's kernel is configured to reserve some memory for Xen only, which does not appear as free memory to the usual tools when logged into the host.

Submitted by farenheitcx on Sun, 11/22/2015 - 20:50

From my dom0 kernel config, I have 1024 MB reserved for dom0. Is there a way to change that and Webmin read the total memory from the system?

Here is the output for that command

# grep dom0_mem /boot/grub/*
/boot/grub/grub.conf: kernel /xen.gz dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all
/boot/grub/menu.lst: kernel /xen.gz dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all

Thanks.

Submitted by JamieCameron on Sun, 11/22/2015 - 23:52

So you can remove the dom0_mem=1024M directive from the Grub config, which will allow the host system to use all available memory for non-VM processes. However, this also means that it is possible for a VM to be unable to start due to RAM being used for other purposes.

Also, in Cloudmin on the Edit System page, you should see a separate memory usage graph which shows RAM available for VM hosting (which should be the full 8 GB).

Submitted by farenheitcx on Mon, 11/23/2015 - 22:09

Thank you! Now I have a better info about the memory available and consumed by xen instances and other process in the server.

Here a new screenshot with fixed memory in Webmin/Cloudmin