尝试给虚拟机 i-23gst39so 添加内存
[[email protected]:/home/admin]
$sudo xm list | grep i-23gst39so
i-23gst39so.3048243.311136 1344 8192 4 r----- 1888.2
[[email protected]:/home/admin]
$sudo virsh dumpxml i-23gst39so.3048243.311136 | grep -i memo
<memory>8388608</memory>
<currentMemory>8388608</currentMemory>
物理服务器 AY66N 10.154.177.160
检查配置
[[email protected]:/home/admin]
$sudo virsh dominfo i-23gst39so.3048243.311136
Id: 1336
Name: i-23gst39so.3048243.311136
UUID: cede2fda-78f2-4806-b204-d86883dc37e1
OS Type: hvm
State: running
CPU(s): 4
CPU time: 128431.4s
Max memory: 8392704 kB
Used memory: 8392668 kB
Autostart: disable
设置内存
sudo virsh setmem i-23gst39so.3048243.311136 16384M
但是比较奇怪，但是发现没有生效
[[email protected]:/home/admin]
$sudo virsh dominfo i-23gst39so.3048243.311136
Id: 1336
Name: i-23gst39so.3048243.311136
UUID: cede2fda-78f2-4806-b204-d86883dc37e1
OS Type: hvm
State: running
CPU(s): 4
CPU time: 129163.6s
Max memory: 8392704 kB
Used memory: 8392668 kB
Autostart: disable
原来这个是xen的系统，居然不能使用virsh来调整
改为xm
sudo xm mem-set i-23gst39so.3048243.311136 16384
但是报错
Error: memory_dynamic_max must be less than or equal to memory_static_max
Usage: xm mem-set <Domain> <Mem>
Set the current memory usage for a domain.
先设置DomU max memory
sudo xm mem-max i-23gst39so.3048243.311136 16384
然后再设置内存就不再报错
sudo xm mem-set i-23gst39so.3048243.311136 16384
检查发现显示内存已经扩容
$sudo xm list | grep i-23gst39so.3048243.311136
i-23gst39so.3048243.311136 1336 16384 4 r----- 131582.9
不过，虚拟机内部cat /proc/meminfo依然显示8G
[root@emr-header-1 proc]# cat /proc/meminfo
MemTotal: 8058056 kB
MemFree: 312760 kB
Buffers: 43488 kB
Cached: 3431344 kB
SwapCached: 0 kB
Active: 6166360 kB
Inactive: 1295604 kB
Active(anon): 4590644 kB
Inactive(anon): 873464 kB
Active(file): 1575716 kB
Inactive(file): 422140 kB
此时使用 sudo virsh dominfo i-23gst39so.3048243.311136 可以看到Used memory 依然是 8G
Id: 1344
Name: i-23gst39so.3048243.311136
UUID: cede2fda-78f2-4806-b204-d86883dc37e1
OS Type: hvm
State: running
CPU(s): 4
CPU time: 2194.3s
Max memory: 16777216 kB
Used memory: 8392668 kB
Autostart: disable
参考 Xen VPS not reflecting the RAM upgrade using xm mem-set
原来在虚拟机内部需要使用 Linux Memory Hotplug ，这个 Linux Memory Hotplug 提供了访问 /sys/devices/system/memory 的sysfs接口，这样可以通过写入 /sys/devices/system/memory/memory[number]/state 来激活或关闭模块。
VMWare KB article 提供了设置步骤方法。
检查
grep line /sys/devices/system/memory/*/state
但是我发现都是online状态
/sys/devices/system/memory/memory0/state:online
/sys/devices/system/memory/memory10/state:online
...
/sys/devices/system/memory/memory8/state:online
/sys/devices/system/memory/memory9/state:online
Changing a Domain's Memory Size Under Xen
换一台测试虚拟机 houyiecsay-1423698772021.187469.48154 10.175.192.6 ，物理服务器是10.154.173.10
- 先检查虚拟机内存配置显示是512M
sudo xm list | grep houyiecsay-1423698772021.187469.48154
houyiecsay-1423698772021.187469.48154 829 512 1 -b---- 98701.3
sudo virsh dominfo houyiecsay-1423698772021.187469.48154
Id: 829
Name: houyiecsay-1423698772021.187469.48154
UUID: 24e3f190-a43f-4d73-a6d5-6b03a14610eb
OS Type: hvm
State: idle
CPU(s): 1
CPU time: 98700.5s
Max memory: 528384 kB
Used memory: 528348 kB
Autostart: disable
虚拟机内部检查
cat /proc/meminfo
MemTotal: 500472 kB
MemFree: 12456 kB
Buffers: 137420 kB
Cached: 112464 kB
- 设置内存改成1G
sudo xm mem-max houyiecsay-1423698772021.187469.48154 1024
sudo xm mem-set houyiecsay-1423698772021.187469.48154 1024
- 此时检查虚拟机内存可以看到
sudo virsh dominfo houyiecsay-1423698772021.187469.48154
显示内存最大1G，但是使用了512M
Max memory: 1048576 kB
Used memory: 528348 kB
检查了虚拟机内部sysfs接口的/sys/devices/system/memory/memory*/state，发现在物理服务器上调整虚拟机的内存都没有变化。究竟如何让虚拟机操作系统能刷新出内存配置的变化？
动态调整XEN虚拟机的CPU
在domU配置，你需要设置maxvcpus来设置允许的虚拟cpu数量，如果没有设置这个maxvcpus，则这个值默认和vcpus相等。
#vcpus - number of VCPUs to boot the system with.
vcpus = 2;
#maxvcpus - maximum number of VCPUs (total) that can be hot added later.
maxvcpus = 8;
maxvcpus需要在domU创建的时候设置，运行状态的vm无法动态修改maxvcpus，所以要让虚拟机能够伸缩，建议提前设置好一些余量。
- 动态添加vcpu
sudo xm list | grep houyiecsay-1423698772021.187469.48154
显示是1个cpu
houyiecsay-1423698772021.187469.48154 829 1024 1 -b---- 98714.9
- 动态设置vcpu
sudo xm vcpu-set houyiecsay-1423698772021.187469.48154 4
显示报错
Error: Cannot set vcpus greater than max vcpus on running domain
Usage: xm vcpu-set <Domain> <vCPUs>
Set the number of active VCPUs for allowed for the domain.
也就是要先修改 vcpumax设置。这个设置似乎不能动态调整，要在虚拟机创建时即设置好。