Mathok :
2012/10/17 Alan Johnson <[email protected] <mailto:[email protected]>>
On Wed, Oct 17, 2012 at 5:02 PM, Mathok <[email protected]
<mailto:[email protected]>> wrote:
Same here with ovirt 3.1.0-2 i can't see a change in the UI.
But i'm able to start more VMs and hava a higher usag of my
swap partiotion so i think the change had the desired effect
Oh, does this take advantage of host swap space as well? I
thought I had read oVirt could do that somewhere, but I have been
reading about so many different virtualization systems over the
last few months that when the RHEV 3.1 Admin Guide
<https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Virtualization/3.1-Beta/html-single/Administration_Guide/index.html>
did not mention swap space in section "4.2.2.2. Memory
Optimization Settings Explained", I was not sure if it applied
here. This is all it says at the moment:
"Memory page sharing allows virtual machines to use up to 200%
of their allocated memory by utilizing unused memory in other
virtual machines. This process is based on the assumption that
the virtual machines in your Red Hat Enterprise Virtualization
environment will not all be running at full capacity at the
same time, allowing unused memory to be temporarily allocated
to a particular virtual machine."
Do you have a reference handy that confirms and explains this? I
put some speedy SSDs in my hosts to hopefully take advantage of
this (and maybe run gluster), so I am hoping to see that in print
somewhere. I'll dig it up if you don't have it handy, but a
confirmation that this is your experience and understanding would
make me feel better in the mean time.
let me explain my (now fixed) problem i have a ovirt host with 8 GB
Ram and 12 VMs every with 256 MB Physical Memory Guarantee. When i
start my two mysql-cluster vms they will use the 256 PMG plus 3,75 GB
MS they have defined a max of 4 GB MS. At this poitn now the problem
begins the mysql taken the hole memory in both vms and now there is no
more free ram at the host and it is not possible to start more vms.
In my understanding, you need to hard cap the physical memory used by
the cluster VM. That will make sure all of the physical memory used by
the VM will not exceed the cap, say 2G. In total, the two cluster VMs
will use 4G memory at most, then the host will have 4G memory at least
to start other VMs. Is that what you want?
(this is also speculation im not a expert) So i need for my
understanding a higher rate of memory overcommit to be able to start
all vms, and for that the host must use the swap to have enough memory
for overcomit to start all vms and yes the higher the rate, the worse
the performance. I'm not sure if this is the right or good way tho fix
this problem
(sorry for my bad english I hope this is understandable)
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?? Shu Ming
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Tel: 86-10-82451626 Tieline: 9051626 E-mail: [email protected] or
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