[ovirt-users] Memory and swap issue

[Itamar Heim]

On 06/05/2014 10:36 PM, Jeff Clay wrote:
> I'm concerned about disabling it and having unexpected behavior if the
> system actually does end up using all of its swap space. Any insight?

change the percentage threshold then.
the idea is if you are swapping - its bad.
though, if you also have a lot of free memory, its kind of absurd to 
block because there is a swap, but its not needed so it remains swapped.


>
> On Jun 5, 2014 2:34 PM, "Itamar Heim" <iheim at redhat.com
> <mailto:iheim at redhat.com>> wrote:
>
>     On 06/05/2014 10:30 PM, Jeff Clay wrote:
>
>         126455 MB total, 863 MB used, 125592 MB free
>            That's what I'm showing right now, but I don't have as many VM's
>         running at the moment. There are currently 8 running and I was
>         getting
>         that issue yesterday when I got around the 15 vm mark.
>
>
>
>
>
>
>
>
>
>
>
>         On Thu, Jun 5, 2014 at 2:07 PM, Itamar Heim <iheim at redhat.com
>         <mailto:iheim at redhat.com>
>         <mailto:iheim at redhat.com <mailto:iheim at redhat.com>>> wrote:
>
>              On 06/05/2014 02:24 AM, Jeff Clay wrote:
>
>                  I'm getting the following error trying to start a VM. I
>         have 64
>                  gb of
>                  RAM on this host. I got this error once before and
>         found that my
>                  swap
>                  partition was only 2gb or so. I increased the swap size
>         to 124GB
>                  and the
>                  problem went away. Below is the error when trying to
>         start a VM and
>                  below that is what my output from "free -g". I don't
>         see why I'm
>                  getting
>                  a swap file error when there's plenty of it available.
>
>
>                     * Cannot run VM. Host swap percentage is above the
>         defined
>                  threshold.
>
>                       - Check your configuration parameters for Host
>         Swap Percentage.
>                     * Cannot run VM. There is no host that satisfies current
>                  scheduling
>
>                       constraints. See below for details:
>                     * The host USARPAOVRTHOST02 did not satisfy internal
>         filter
>                  Memory.
>
>
>
>
>                  [root at usarpaovrthost02 ~]# free -g
>                                 total       used       free     shared
>           buffers
>                       cached
>                  Mem:            62         62          0          0
>               0
>                         12
>                  -/+ buffers/cache:         50         12
>                  Swap:          123         12        110
>                  [root at usarpaovrthost02 ~]#
>                  [root at usarpaovrthost02 ~]#
>                  [root at usarpaovrthost02 ~]# swapon -s
>                  Filename                                Type
>           Size    Used
>                  Priority
>                  /dev/dm-1                               partition
>         129490936
>                  12811000        -1
>                  [root at usarpaovrthost02 ~]#
>
>
>
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>
>              what do you see under host general subtab for swap percentage?
>
>
>
>     iirc, you can either disable the swap check via the config
>     EnableSwapCheck, or change the threshold via
>     BlockMigrationOnSwapUsagePerce__ntage
>     (which would be a confusing name if it affects RunVm and not only
>     migration...)
>