Rafael, - It's easy to configure and run ZK either in single node or cluster - zookeeper should replace mysql locking mechanism used inside ACS code (places where ACS locks tables or rows).
I don't think from the other size, that moving from MySQL locks to ZK locks is easy and light and (even implemetable) way. 2017-12-18 16:20 GMT+07:00 Rafael Weingärtner <rafaelweingart...@gmail.com>: > How hard is it to configure Zookeeper and get everything up and running? > BTW: what zookeeper would be managing? CloudStack management servers or > MySQL nodes? > > On Mon, Dec 18, 2017 at 7:13 AM, Ivan Kudryavtsev < > kudryavtsev...@bw-sw.com> > wrote: > > > Hello, Marc-Aurele, I strongly believe that all mysql locks should be > > removed in favour of truly DLM solution like Zookeeper. The performance > of > > 3node ZK ensemble should be enough to hold up to 1000-2000 locks per > second > > and it helps to move to truly clustered MySQL like galera without single > > master server. > > > > 2017-12-18 15:33 GMT+07:00 Marc-Aurèle Brothier <ma...@exoscale.ch>: > > > > > Hi everyone, > > > > > > I was wondering how many of you are running CloudStack with a cluster > of > > > management servers. I would think most of you, but it would be nice to > > hear > > > everyone voices. And do you get hosts going over their capacity limits? > > > > > > We discovered that during the VM allocation, if you get a lot of > parallel > > > requests to create new VMs, most notably with large profiles, the > > capacity > > > increase is done too far after the host capacity checks and results in > > > hosts going over their capacity limits. To detail the steps: the > > deployment > > > planner checks for cluster/host capacity and pick up one deployment > plan > > > (zone, cluster, host). The plan is stored in the database under a > VMwork > > > job and another thread picks that entry and starts the deployment, > > > increasing the host capacity and sending the commands. Here there's a > > time > > > gap between the host being picked up and the capacity increase for that > > > host of a couple of seconds, which is well enough to go over the > capacity > > > on one or more hosts. A few VMwork job can be added in the DB queue > > > targeting the same host before one gets picked up. > > > > > > To fix this issue, we're using Zookeeper to act as the multi JVM lock > > > manager thanks to their curator library ( > > > https://curator.apache.org/curator-recipes/shared-lock.html). We also > > > changed the time when the capacity is increased, which occurs now > pretty > > > much after the deployment plan is found and inside the zookeeper lock. > > This > > > ensure we don't go over the capacity of any host, and it has been > proven > > > efficient since a month in our management server cluster. > > > > > > This adds another potential requirement which should be discuss before > > > proposing a PR. Today the code works seamlessly without ZK too, to > ensure > > > it's not a hard requirement, for example in a lab. > > > > > > Comments? > > > > > > Kind regards, > > > Marc-Aurèle > > > > > > > > > > > -- > > With best regards, Ivan Kudryavtsev > > Bitworks Software, Ltd. > > Cell: +7-923-414-1515 > > WWW: http://bitworks.software/ <http://bw-sw.com/> > > > > > > -- > Rafael Weingärtner > -- With best regards, Ivan Kudryavtsev Bitworks Software, Ltd. Cell: +7-923-414-1515 WWW: http://bitworks.software/ <http://bw-sw.com/>
