FogBugz was still on twelve ElasticSearch 1.6 nodes when I left in 2018. We also had a custom plugin (essentially requesting facets that weren't stored in ElasticSearch back from FogBugz), which was the main reason we hadn't spent much time thinking about upgrading it. To keep performance adequate, we scheduled cache flush operations that, even at the time, we knew were pants-on-head crazy to be doing in production. I can't remember if we were running 32-bit or 64-bit with Compressed OOPs.
Kiln was on an even older version, v1.4 if I remember correctly. And one of the shards had a corruption warning, yet it didn't seem to affect stability or results. But that wasn't a fun cluster to operate, since it refused to do certain types of maintenance because of the supposed corruption.
Hopefully the newer versions are easier to migrate between. I don't remember what exactly was preventing us from upgrading, but I'm sure part of it was wanting to avoid a full reindex.
It's good to hear stories of real-world systems. If you only look at blog posts you get the idea that everyone is doing everything perfectly, but of course it's not really like that at all...
FogBugz was still on twelve ElasticSearch 1.6 nodes when I left in 2018. We also had a custom plugin (essentially requesting facets that weren't stored in ElasticSearch back from FogBugz), which was the main reason we hadn't spent much time thinking about upgrading it. To keep performance adequate, we scheduled cache flush operations that, even at the time, we knew were pants-on-head crazy to be doing in production. I can't remember if we were running 32-bit or 64-bit with Compressed OOPs.
Kiln was on an even older version, v1.4 if I remember correctly. And one of the shards had a corruption warning, yet it didn't seem to affect stability or results. But that wasn't a fun cluster to operate, since it refused to do certain types of maintenance because of the supposed corruption.
Hopefully the newer versions are easier to migrate between. I don't remember what exactly was preventing us from upgrading, but I'm sure part of it was wanting to avoid a full reindex.