-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 I've gone through the great post[1] by Meltwater and a couple of things caught my eye.
One of which is "The only thing we noticed inside Riak, that correlated to the elevated load, was that it dropped its internal caching structures, the ETS tables. This was pointing to a memory issue" They don't mention what backend they're using but I'm guessing it's LevelDB. As far as I know Bitcask relies on file system caches[2] and 'memory' backend which is basically ETS tables isn't such a great idea for persistence. Since levelDB does indeed do caching[3] it's kind of clear that it's all about it. I've mostly used Riak with Bitcask backend so I'm not familiar with LevelDB inner plumbings. What I would like to know is how they figured out that Riak is dropping the levelDB backend caching. Was it simply monitoring ETS heap size[4] or is there a metric available that I have overlooked? Thanks, Sam [1] http://underthehood.meltwater.com/blog/2015/04/14/riak-elasticsearch-and-numad-walk-into-a-red-hat/ [2] "Bitcask depends on filesystem caches" http://docs.basho.com/riak/latest/ops/advanced/backends/bitcask/ [3] leveldb.maximum_memory.percent http://docs.basho.com/riak/latest/ops/advanced/backends/leveldb/#Installing-eLevelDB [4] memory_ets http://docs.basho.com/riak/latest/ops/running/nodes/inspecting/ -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJVgIgYAAoJEO4RrVgri0dn4aUQAJgKV/WVzlailww8u+5Zb/0H KRETcobF3GB0OUIC9N3LxThbB8CuEFk3Ii+dCz79iq5Kt2esY3m5ekKwq1No2NvS ONNAB56Me23XidHP12B46FffpYRgMuVuF7j/Vwj3M+B/bo11mrl5vK+mcMLkp5oD sveMIOpGvtZTryeYLXDYCIAvy0zzq2NlXq6SIkzlkywblVC97X9HNf7htBYv0xm4 kfMowENGMSF4XifhN4gnk8C+r555DkOHHEk6ld2gNcf+werMDhHgD+r4mATISwCX t4ilmYI9yaRZyS/Y7BaT6/uT+h1lZBsHHsivvLeS8Baws+C9uotaty46U5oQKMWL LeUgj8RVm5hh8IByiVhLrFA3HV1UtNURi3+/LzJvMJgM7L4kAhyRDHy6JC3Cc62X fytsgBTtk7qbOgYYeuwZZVN+60fCQfA++ADq+aLQSb5dLqI8gJI3cTguAru7fSga mGnUqQsHlFf0AS7SJ6Uc3FnfWaB56rjMJak3FN95hJVZ3QY4D1cj4/l7PcKTBxOO YXW/1FAYxdQEzQ7X6WtYNVdFnAlVHROgC8ymKbuobko51XnnVHq/VihcMpqUskjF 7g2/jO6MJz2fdka7e43Yeahi2oBjkdkf7kK2P7hb1C69Br9Dqy7NnKRrqfNhz3sE eIXucnJLZvs4CJJ4WpCr =gte+ -----END PGP SIGNATURE-----
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