Mengü Yazıcıoğlu spoke next about what we are pretty sure is the biggest Koha installation, a cluster serving 1132 Public libraries. (They are growing so fast it has moved from 1126 to 1132 libraries in the last 2 weeks)
They have been live on Koha for 2 years it is run as a project from the Ministry of Culture and Heritage.
In 2012 MCH signed with Near East University in Cyprus to migrate to Koha 2.2.x. With 900,000 users and 9,000,000 items for the migration. Lots of problems with dirty data, centralising a decentralised model meant lots of duplicates. They also had problems with infrastructure and lack of training. But they worked through this and had a system that worked well.
They made quite a few customisations and scripts to deduplicate biblios, the Ministry of Culture and Heritage estimates they saved 5,000,000 Euros on not having to have people do the deduplication alone.
In December 2015 they upgraded to Koha 3.20.x.
You can return your item anywhere in Turkey, so they make heavy use of the Koha transfers module, which tracks where any item is.
The infrastructure to run this, is a lot less than most people would think I am sure. Here is their infrastructure
This was a fascinating and amazing presentation. Started in Levin, Foxton, Shannon and Tokomaru, now … 1132 cities and towns in Turkey .. mind blowing.