[ovs-discuss] OVN Database sizes - Auto compact feature

Daniel Alvarez Sanchez dalvarez at redhat.com
Wed Mar 7 13:40:19 UTC 2018

Hi folks,

During the performance tests I've been doing lately I noticed
that the size of the Southbound database was around 2.5GB
in one of my setups. I couldn't dig further then but now I
decided to explore a bit more and these are the results in
my all-in-one OpenStack setup using OVN as a backend:

* Created 800 ports on the same network (logical switch).
* Deleted those 800 ports.
* I logged the DB sizes for both NB and SB databases every second.

See attached image for the results.

At around x=2000, the creation task finished and deletion starts.
As you can see, there's automatic compact happening in the
NB database across the whole test. However, while I was deleting
ports, the SB database stop shrinking and keeps growing.

After the test finished, the DB sizes remaining the same
thus SB database being around 34MB. It was not until I
manually compacted it when it finally shrinked:

[stack at ovn ovs]$ ls -alh ovnsb_db.db
-rw-r--r--. 1 stack stack 34M Mar  7 12:04 ovnsb_db.db

[stack at ovn ovs]$ sudo ovs-appctl -t
/usr/local/var/run/openvswitch/ovnsb_db.ctl ovsdb-server/compact

[stack at ovn ovs]$ ls -alh ovnsb_db.db
-rw-r--r--. 1 stack stack 207K Mar  7 13:32 ovnsb_db.db

I'll try to investigate further in the code.

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