Hi Community, I try to encounter how HA works. Our goal is it to make it usable with managed storage like (Netapp Solidfire / maybe it works with CEPH too) so if its possible.
This is a good guide and for some times we fixed and added the missing keys. https://cwiki.apache.org/confluence/display/CLOUDSTACK/High+Availability+Developer%27s+Guide<https://cwiki.apache.org/confluence/display/CLOUDSTACK/High+Availability+Developer's+Guide> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Host+HA In the database I found out there are three different types of HA. If you select in the configuration table "SELECT * FROM `configuration` WHERE `component` LIKE '%ha%' LIMIT 0,1000;“ you will get three types of components. 1. HAManager 2. HighAvailbilityManager 3. KVMHAConfig "HAManager and HighAvailbilityManager" are the base which was extended from Rohit with „KVMHAConfig“ - KVM with stonith fencing. I understand all things work together but maybe I need to understand the process a little bit better. ------------------------------------------------------------------------------------ To clarify I write down what I think to each of them. This is what I understand but please correct me or help me to understand it a little bit better. —>I found out that if we use managed storage a restart of virtual machines only works on the same host. This is what I understand the lack of the missing heartbeat file on the shared storage because we don’t have shared storage like NFS. — "If the network ping investigation returns that it cannot detect the status of the host, CloudStack HA then relies on the hypervisor specific investigation. For VMware, there is no such investigation as the hypervisor host handles its own HA. For XenServer and KVM, CloudStack HA deploys a monitoring script that writes the current timestamp on to a heartbeat file on shared storage." — And — For the initial release, only KVM with NFS storage will be supported. However, the storage check component will be implemented in a modular fashion allowing for checks using other storage platforms(e.g. Ceph) in the future. — ------------------------------------------------------------------------------------ We would implement a plugin or extend this for managed storage but at the moment I need to understand where this should happen. Since managed storage uses different volumes for each VM we should its not easy to make an storage heartbeat like NFS. the lack of one missing volume don’t means the hole storage has an problem so I think its not easy to encounter from one volumes to a complete storage. We don’t use KVMHAConfig a the moment and encounter that if a Host goes down (offline) the virtual machines will not be restarted on another host. They will only restarted on the host if the host comes back.(online). We don’t want a hard fencing of the hosts but we want a correct determination whether the host is still alive. Fencing would maybe in our case a little bit hard because we don’t have an hard data corruption on entire storage. Some questions. 1. let's assume correctly that the HA don’t work without an shared storage and network ping? Is this the cause why our virtual machines will not restarted on another host? Is this correct or do we have an config problem? 2. Where could the plugin be implemented? Is there a preferred place? 3. If point 1. Is correctly I thought the idea would be to add an global flag to use the secondary storage (NFS) as heartbeat to find out if there is any host inactive? Thanks and Cheers Sven __ Sven Vogel Lead Cloud Solution Architect EWERK DIGITAL GmbH Brühl 24, D-04109 Leipzig P +49 341 42649 - 99 F +49 341 42649 - 98 s.vo...@ewerk.com www.ewerk.com Geschäftsführer: Dr. Erik Wende, Hendrik Schubert, Tassilo Möschke Registergericht: Leipzig HRB 9065 Support: +49 341 42649 555 Zertifiziert nach: ISO/IEC 27001:2013 DIN EN ISO 9001:2015 DIN ISO/IEC 20000-1:2011 ISAE 3402 Typ II Assessed EWERK-Blog<https://blog.ewerk.com/> | LinkedIn<https://www.linkedin.com/company/ewerk-group> | Xing<https://www.xing.com/company/ewerk> | Twitter<https://twitter.com/EWERK_Group> | Facebook<https://de-de.facebook.com/EWERK.IT/> Auskünfte und Angebote per Mail sind freibleibend und unverbindlich. Disclaimer Privacy: Der Inhalt dieser E-Mail (einschließlich etwaiger beigefügter Dateien) ist vertraulich und nur für den Empfänger bestimmt. Sollten Sie nicht der bestimmungsgemäße Empfänger sein, ist Ihnen jegliche Offenlegung, Vervielfältigung, Weitergabe oder Nutzung des Inhalts untersagt. Bitte informieren Sie in diesem Fall unverzüglich den Absender und löschen Sie die E-Mail (einschließlich etwaiger beigefügter Dateien) von Ihrem System. Vielen Dank. The contents of this e-mail (including any attachments) are confidential and may be legally privileged. If you are not the intended recipient of this e-mail, any disclosure, copying, distribution or use of its contents is strictly prohibited, and you should please notify the sender immediately and then delete it (including any attachments) from your system. Thank you.
