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From Darrel Schneider <dschnei...@pivotal.io>
Subject Re: Off-heap support deactivation
Date Wed, 02 Oct 2019 15:37:51 GMT
You can change it but only while the servers hosting that region are
stopped. In the pre-cluster-config world, users did this by stopping the
servers, editing their cache.xml (and altering the disk-store) and then
starting the servers. But as my previous email said, it can be hard to do
with gfsh.

On Wed, Oct 2, 2019 at 1:44 AM Alberto Bustamante Reyes
<alberto.bustamante.reyes@est.tech> wrote:

> thanks for the detailed explanation Darrel.
>
> There is something I did not get: "alter disk-store" is used to align the
> region info the disk store has when a region attribute is changed. But
> off-heap support is an attribute that cannot be changed on a region after
> it is created. So then, what is the utility of being able to run "alter
> disk-store" with "--off-heap" parameter if that is something that will not
> change in the region?
>
> ________________________________
> De: Darrel Schneider <dschneider@pivotal.io>
> Enviado: lunes, 30 de septiembre de 2019 17:51
> Para: dev@geode.apache.org <dev@geode.apache.org>
> Asunto: Re: Off-heap support deactivation
>
> You can specify this setting at the time you create the region. Geode does
> not have support for changing it on a region that already exists. Only a
> few region attributes can be changed on a region that currently exists (see
> the AttributesMutator API). So how is your region getting created? I think
> it is probably from cluster configuration. So what you would need to do is
> get the definition stored in cluster configuration. I don't think the gfsh
> alter region command will let you change this attribute (alter region uses
> AttributesMutator). So you either need to delete the current definition and
> then create it again or you need to edit the current definition manually.
> Using gfsh to destroy and create is the cleanest solution, but that will
> also blow away the data you currently have persisted.
> To change it manually you can use gfsh export to get your cluster config as
> xml, edit the xml to change the offheap boolean property on the region, and
> then use gfsh import to load the xml you edited. This requires that the
> server are restarted.
> If you are not using cluster config (I think you should be) then this is
> actually easier. You either just edit your cache.xml file and restart the
> server that is using it or you just change your code's use of RegionFactory
> to create the region differently.
>
> The whole alter disk-store thing is just an optimization. The region
> attributes stored in the disk-store for a persistent region do not
> determine how the region is configured. The cluster-config/xml/apis that
> create the region do that. When a disk-store is initially loaded it does
> not yet know how the regions are configured. But it creates some temporary
> maps that are used later once the region is created. If the attributes
> stored in the disk-store match those on the region configuration then the
> region initialization will be faster and use less memory. So basically if
> you do have a persistent region and then change how it is configured, if
> you also then alter how it is configured on the disk-store you next restart
> will recover faster. If you don't do the alter disk-store the first
> recovery will be slower but the actual region config will be stored again
> in the disk-store and subsequent recoveries will be fast.
>
> On Mon, Sep 30, 2019 at 8:28 AM Alberto Bustamante Reyes
> <alberto.bustamante.reyes@est.tech> wrote:
>
> > Hi all,
> >
> > Is it possible to change the off-heap support of a region once it is
> > created? The idea I got from documentation is that it is possible to do
> it
> > if the region is persistent, as the off-heap flag of the region can be
> > changed using "alter disk-store".
> >
> > I have run the following example to check it: with two servers, I created
> > a partition persistent region, with off-heap set to true. Then I
> > deactivated the off-heap support by using alter disk-store, as described
> in
> > documentation. But I have observed that if I run "describe region", the
> > off-heap flag is still set to true. And if I populate entries, the values
> > are stored in the off-heap memory.
> >
> > Did I misunderstood the documentation or I did something wrong?
> >
> > Thanks in advance,
> >
> > Alberto B.
> >
> >
> > PD: I wrote down the steps I followed in the following gist:
> > https://gist.github.com/alb3rtobr/e1fcf4148fe46f2e7b9e02a2e458624c
> >
>

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