In my experience, you're usually MUCH better off adding more resources to your single database server.
For any given server purchase, there is a cost per performance breaking point where it starts to make more sense to buy two (or more) smaller servers for the same performance vs one large server. It's been a couple years, but the last time I checked the breaking point was something like 64GB RAM and 2 16-core CPUs. You can serve a lot of books to a lot of patrons on a machine like that. Joel Coehoorn Director of Information Technology York University of Nebraska On Wed, Jul 27, 2022 at 7:49 PM <[email protected]> wrote: > Hi Admire, > > You'll probably have more luck asking on the dev listserv: > [email protected]. However, I'll try to offer some > insight here. I'm also CCing in Mengu who has probably the biggest > horizontally scaled out Koha in the world. > > Off the top of my head, technically you could have a load balancer in > front of multiple Koha application servers. You'd want to make sure that > the cronjobs are only running on 1 application server though. You also > would probably want to use an external Elasticsearch cluster since Zebra > would be a bottleneck. In theory, you could use a multi-master > MySQL/MariaDB database cluster, but I don't know if anyone has done that > (and I'd be concerned about the "eventual consistency" of multi-master > setups). If you wanted to a master-replica cluster, you'd need to patch > Koha to allow for read-only connections (for things like the Reports > module); at the moment, Koha can only use 1 read/write database connection. > You'd also need to move your RabbitMQ server to an external server which is > problematic with the koha-common package at the moment (but there are > ways). (Note: I may be missing another horizontal scaling issue, but these > are what come to mind at the moment. You might need to use a network share > for some file system resources in /var/koha/* but I can't recall off the > top of my head.) > > It would be much easier to scale vertically. I'd suggest you do some > analysis to see where your key pain points are. > - Out of the box, Koha only uses 2 Starman/Plack workers, so if it's a > case where your Koha is overwhelmed by legitimate traffic, I'd recommend > adding more Starman/Plack workers via koha-conf.xml (if you have the CPU > and RAM to spare). > - If your Koha is slow, you might want to look at your database's I/O > performance as well. Using quality SSDs can make a huge difference for > database driven applications. (Note also that having MySQL/MariaDB on an > external server is a common practice but technically speaking it does add > some latency to database transactions which you wouldn't have if you ran > MySQL/MariaDB on the same server and used Unix sockets. For very large Koha > databases, we've noticed that having an external DB server adds too much > latency.) > - If you're getting a lot of traffic, you should check to see how much > traffic is from bots. You might need to implement something like fail2ban > to block bots that put too much load on your system. Typically, I find when > Koha is overwhelmed, it's due to bots. (You can experiment with a > robots.txt file to help with this but it's not a completely effective > solution.) > > There's lots of things to explore. > > In the long-term I'd love to make Koha easier to scale horizontally (and > ideally deploy as a load-balanced containerized application) but there's > work to do and not much demand for it from libraries, so I don't think it's > a priority for devs at the moment, unfortunately. > > Anyway, I hope that helps! > > David Cook > Senior Software Engineer > Prosentient Systems > Suite 7.03 > 6a Glen St > Milsons Point NSW 2061 > Australia > > Office: 02 9212 0899 > Online: 02 8005 0595 > > -----Original Message----- > Message: 10 > Date: Wed, 27 Jul 2022 16:28:12 +0100 > From: Admire Mutsikiwa <[email protected]> > To: [email protected] > Subject: [Koha] n-Tier deployment of Koha > Message-ID: > <CAD4nctbymX-UfziZr67h-4p4O0GBPapecRCXfc= > [email protected]> > Content-Type: text/plain; charset="UTF-8" > > My Koha implementation is sometimes overwhelmed as it is a two-tier > implementation with a database on one server and a Koha application on > another server. I am wondering if it is possible to have a 3 or 4 tier > deployment architecture, with for instance, having a load balancer, koha > application server and a clustered MySQL/Mariadb implementation. > > Kind Regards, > > -- > > > > *The information transmitted by this email is intended only for the > person or entity to which it is addressed. This email may contain > proprietary, business-confidential, and/or privileged material. If you > are > not the intended recipient of this message, be aware that any use, > review, > retransmission, distribution, reproduction or any action taken > in reliance > upon this message is strictly prohibited. If you received > this in error, > please contact the sender and delete the material from > all computers* > > _______________________________________________ > > Koha mailing list http://koha-community.org > [email protected] > Unsubscribe: https://lists.katipo.co.nz/mailman/listinfo/koha > _______________________________________________ Koha mailing list http://koha-community.org [email protected] Unsubscribe: https://lists.katipo.co.nz/mailman/listinfo/koha
