wohali commented on issue #796: CouchDB Error - No DB shards could be opened URL: https://github.com/apache/couchdb/issues/796#issuecomment-342910514 Looking again at the error reported: ``` [error] 2017-09-06T12:54:23.113497Z couchdb@localhost <0.2166.3> 0ae11b116b rexi_server exit:{timeout,{gen_server,call,[couch_server,{open,<<"shards/00000000-1fffffff/ruum_1491318340205uh4nvaer9gywpo5g3w99.1496998111">>,[{timeout,100},{user_ctx,{user_ctx,<<"admin">>,[<<"_admin">>],<<"cookie">>}}]},100]}} [{gen_server,call,3,[{file,"gen_server.erl"},{line,212}]},{couch_server,open,2,[{file,"src/couch_server.erl"},{line,86}]},{couch_db,open,2,[{file,"src/couch_db.erl"},{line,91}]},{fabric_rpc,open_shard,2,[{file,"src/fabric_rpc.erl"},{line,248}]},{rexi_server,init_p,3,[{file,"src/rexi_server.erl"},{line,139}]}] ``` what we're seeing here is a 100ms timeout on couch_server opening a shard on disk. The likely culprits here are slow EBS store or maxxed out CPU. If you can rule out the second, you are almost certainly being hit by the first. AWS offers higher tiers of EBS that you will want to investigate, and specifically "the highest performance Provisioned IOPS SSD (io1) for latency-sensitive transactional workloads". You will want to ensure at the very least that your data directory (`/opt/bitnami/couchdb/var/lib/couchdb` per above) is on such a volume. You can also improve throughput by not logging to the local node, and instead using [syslog to stream the logs to a separate logging server](https://github.com/apache/couchdb/blob/master/rel/overlay/etc/default.ini#L548-L556). CouchDB is a high-performance product expecting to run on best available hardware. If you're running it in the cloud, you need to be aware of "gotchas" like this.
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