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2020-06-02 15:00:57 -0500 commented question Caching of images in Openstack glance in a multinode set up

Thank you for the answers!

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2020-05-31 13:13:35 -0500 asked a question glance-cache folder permission error

Hi everyone,

I am trying to configure glance-cache and I have set  **image_cache_dir: /var/lib/glance/image-cache**

glance api is running as pod in my controller node.When I am trying to re-deploy glance  service after configuring  image_cache_dir,glance api pod goes into error state

ERROR: [Errno 30] Read-only file system: '/var/lib/glance/image-cache'

Logs:

+ COMMAND=start
+ start
+ exec glance-api --config-file /etc/glance/glance-api.conf
2020-05-31 17:59:47.085 1 INFO glance.image_cache [-] Image cache loaded driver 'sqlite'.
2020-05-31 17:59:47.085 1 INFO glance.image_cache [-] Image cache loaded driver 'sqlite'.
ERROR: [Errno 30] Read-only file system: '/var/lib/glance/image-cache'

How can I fix this?

Thanks for your time.
2020-05-31 06:45:21 -0500 commented question Caching of images in Openstack glance in a multinode set up

Okay & from the Openstack doc" The Glance API server may be configured to have an optional local image cache--" since it is a local image cache and default image_cache_max_size can be 10gb, Should I think of having extra memory configured in controller node?

2020-05-31 06:36:18 -0500 commented question Understanding caching of imaged in openstack glance

Yes,the imgs are cached under /var/lib/nova/ in compute node,& for further instance creation nova-compute doesn't hit Glance but uses its cached img in /var/lib/nova,That is the reason hit count is not getting increased.Is caching of imgs in compute node disabled by cache_image=none in nova.conf?

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2020-05-29 11:10:22 -0500 commented question Caching of images in Openstack glance in a multinode set up

Bernd,Thank you very much for clarifying.That url ref was just for the img used there to depict instance creation.Now will I see any performance difference if my Glance backend is the default FileSystem storage backend Or When should I use Glance caching & How can I effectively measure the performan

2020-05-29 09:57:58 -0500 commented question Caching of images in Openstack glance in a multinode set up

If I have to follow the Instance creation steps as mentioned in the diagram: https://maestropandy.wordpress.com/2016/05/26/openstack-instance-creation-request-work-flow/ (https://maestropandy.wordpress.com/20...) With Cache configured ,Instance creation flow is Nova-Compute-->Glance Api-->Picks Cached Image instead of Hitting Img store?

2020-05-29 09:57:53 -0500 asked a question Understanding caching of imaged in openstack glance
 Hi everyone,

I am understanding caching of glance imgs in a multinode environment while I am setting up the env

Openstack set up:

Openstack version:5.2.0

Deployed as openstack-helm(Openstack deployed on K8S nodes)-All the services are running as PODS on controller 
node.There is 1 Controller node and 2 compute nodes.

Controller node glance API is configured for image caching i.e

middleware is configured which was done by default under 
paste.filter_factory = glance.api.middleware.cache_manage:CacheManageFilter.factory
flavor is set as keystone+cachemanagement 
and image_cache_max_size and image_cache_dir are also defined

And I created an Instance

And when I executed glance-cache-manage list-cached list on the controller node
it does list cached Images in the below format

Found 1 cached images...
+--------------------------------------+----------------------------+----------------------------+-----------+------+
|                  ID                  |    Last Accessed (UTC)     |    Last Modified (UTC)     |      Size | Hits |
+--------------------------------------+----------------------------+----------------------------+-----------+------+


My Question:

When does the column Hits(int) gets incremented?--Because Hits value changed from 0 to 1 and 
doesnt change further even though I have created multiple instances on the 2 compute nodes using this same Image 
which is cached. 

 1. Is it because the images are cached
    on both the compute nodes and
    nova-compute doesn't hit the glance
    from the 3rd  instance creation?
        - if its 'yes' what is the location where the image is cached
          on the compute node.
       - And if 'no' and the flow is Nova-compute -->Glance api-->Glance cache
        why is the Hits not getting increased? Did I miss any config?


Please correct me,if my understanding of caching is bad.

I sincerely thank for the time and patience.
2020-05-29 07:49:01 -0500 commented question Caching of images in Openstack glance in a multinode set up

But What I did see is Image is getting cached in the glance-api pod itself in the same dir as image_cache_dir and this is running in controller node.

2020-05-29 04:29:26 -0500 asked a question Caching of images in Openstack glance in a multinode set up

Hi everyone!

I just want to understand/setup caching of glance images in a multinode environment,where there are 
multiple  controller and compute nodes 

1.Where should the image caching be done,whether it is on the control/compute node?
2.If it is on the compute node, How should I enable the caching of Images on the compute node?
and how should I manage it?
3.how images are selected for caching? how they are updated? And where are they stored?

My Openstack set up:

Openstack version:5.2.0
Deployed as openstack-helm(Openstack deployed on K8S nodes)-All the services are running as PODS on controller 
node.
There is one Controller node-glance api and glance-registry is running as K8s POD here, and there are two compute 
nodes and there are no glance service running on compute nodes.


According to glance documentation http://docs.openstack.org/developer/glance/cache.html (here). , the selection 
of cached images for example is done manually by the administrator of the system, Using this I can configure 
manually,but I am looking on how to enable caching on all compute nodes while deploying.

Thank you!