Re: [Serusers] SER Reports "out of memory"

See inline. Jiri Kuthan wrote: I'm not proposing to use BDB, it was just an example. Databases are very good at replication, even two-way replication can be done quite efficiently through locking etc. I just took Paul's setup with cluster back-end as granted and wrote my comments based on that... Thinking a bit wider and building on your comments, Jiri: The challenge, I think, is to handle the following things in any likely deployment scenario: 1. Usrloc writes to cache vs. DB 2. Replication of usrloc, multiple DBs vs. cluster, across LAN or WAN 3. Memory caching management (inconsistencies etc) For the sake of the readers, here is how I understand SER's operations today: 1. Usrloc is always written to cache, DB write is controlled through write-through parameter 2. Replication is handled by t_replicate 3. Management of cache is not needed, the cache is always updated. However, an updated DB (and thus dirty cache) will not be detected Here is how I understand Paul's proposal (and with my annotated suggestions from my last email :-): 1. Usrloc is always written to DB, cache is updated if it is already in the cache 2. Replication is handled by underlying database across DBs or in a cluster 3. If usrloc is not found, DB is checked. If cache is full, some mechanism for throwing out a usrloc is devised I must admit I often fall for the argument: "let each system do what it is best at." Following that, replication should only be done at an application level if the underlying database is not capable of doing it (if we agree that a DB is good at replication). The only thing I see a DB is not capable of, is handling the NAT issues. So, if a given usrloc has to be represented by different location (ex. the registration server), then the DB cannot do replication. However, if the NAT issue is handled through some other means, ex. Call-Id aware LVS with one public IP, then the usrloc should be the same across DBs and the DB should handle the replication. You don't need many subscribers before you'll want redundancy and as active-passive redundancy is a waste of resources, I believe an upgrade of the replication mechanism should soon be imminent. ;-) I think I have said this before, but this is my enterprise-level "dream" scenario: 1. Two geographically distributed server centers 2. DNS SRV for load distribution (and possible using segmentation of clients through their configurations if they don't support DNS SRV) 3. Each data center has Call-Id sensitive LVS in front, with one or more servers at the back (a fair-sized LVS box can handle 8,000 UDP packets per second) 4. Each data center either has a DB cluster or two-ways SER-based replication 5. The data centers replicate between each other using either DB-based replication or two-ways SER-based replication 6. The SER-based replication is an enhanced version of t_replicate() were replication is to a set of servers and replication is ACKed and guaranteed (queue). I would suggest using the XMLRPC interface Jan has introduced 7. I think Paul's cache-suggestions are good regardless of decisions on replication Entry level scenario where the same box is running LVS, SER, and DB (you can quickly add new boxes) has a very low cost. Do you suggest that no mechanism should be devised when the cache limit is hit? ;-) Then maybe I can suggest an email alert to the operator when a certain amount of the cache is full... :-D I trust my people to act fast and appropriate, but not that fast and appropriate! g-)