Hello Heitor, wt., 23 kwi 2019 o 13:50 Heitor Faria <hei...@bacula.com.br> napisał(a):
> Hello Radoslaw, > > I meditated a lot about this topic, and just to keep it short I will > resume my conclusions: > The main conclusion I wrote in my previous email is a different dictionary we use to describe the same things. Unless we move it to the same level, our dispute is pointless. But, we can go ahead so I'll practice my english. :) > > 1. HA means single points of failure elimination, reliable crossover and > failure detection. > No, High Availability is a solution which allows for service to function with as highest uptime as possible. It should be achieved using SPOF elimination including a single server. I do not understand what a "reliable crossover" is? > I don't see how having two replicated always on Directors (perhaps with > the same Director Name); > You cannot run two always on replicated directors. Why? Every single Bacula Director requires a separate copy of the catalog database. So, two always on directors require two separate databases, so you cannot setup online replication in this setup. It just won't work. > replicated job and client configurations; > Yes, you can achieve this with simple rsync or build in database replication mechanism when using IBAdmin. :) > replicated backup data > Bacula volumes? So you can achieve this with Bacula Copy Jobs. DRBD does not work for tapes, sorry. > and metadata; > I assume as a metadata you are referring to catalog database, so for PostgreSQL you can use a streaming replication and master/standby mode of operation as described in manual: https://www.postgresql.org/docs/9.1/high-availability.html But, the standby instance cannot be used for standard processing queries. The HotStandby - a read only version is available. So you can perform catalog database (metadata) replication, but you cannot use it for two always on Directors. > secondary Director de/activation mechanisms; > ??? I do not understand, why do you need to deactivate secondary Director while it is in always on mode? So is always on mode for secondary Director really necessary? > redundant storage possibility; cannot be considered a High Availability > Solution. > Simple failover procedure for replicated database and Bacula Director above require: - stop a replication for database - stop a configuration replication if implemented - deactivate a main Director - de/activate secondary Director - promote secondary database as a master database - run a secondary Director and promote it as a master - delete all volumes from main storage to promote all replicated copy jobs as main jobs - implement a reverse database replication which requires to delete an old database and make an initial data replication - implement a reverse configuration replication - implement a reverse copy jobs, make an initial volumes replication - until ready (hours? days? weeks?) you cannot make a failback To make a Director failover, you should (it is not strictly required) failover its IP address. To make a SD failover you have to failover its IP address to. You can assign a new IP addresses for both Director and SD but it require to alter configuration before failover. I will undergo a laboratory on that. > As I implement a lot of HA clustering solutions for backup and other systems I'm extremely curious how your solution will work. 3. Every big data center application usually has their native cluster > mechanism, so DRBD+whatever cannot be the considered the silver bullet. In > fact, IMHO, it is a overkill to use your proposal to replicate the Director > service, > I NEVER! proposed to replicate a Director service with HA! Please do not impose it. > and adds a lot of complexity. > I think we should stop our conversation here because it points to nowhere. I think we are talking about the same things using different dictionaries, words sentences, statements, so we do not understand each other. I won't make any followup to this thread. And as always, it was a great pleasure to be able to perform a such interesting conversation. best regards -- Radosław Korzeniewski rados...@korzeniewski.net
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