Hi Simon, The spreadsheet is referenced from the LevelDB's parameter planning [0].
A ring_size defines the number of vnodes (virtual nodes) a riak cluster runs internally, and as each virtual node is implemented as an Erlang process, the bigger the ring_size is, the more memory is required from the operating system. [0] http://docs.basho.com/riak/1.4.12/ops/advanced/backends/leveldb/#Parameter-Planning Regards, Ciprian On Thu, Feb 12, 2015 at 1:44 PM, Simon Hartley < simon.hart...@williamhill.com> wrote: > Hi Ciprian, > > > > Thanks for the answer. > > > > According to Riak doc “Cluster-Capacity-Planning” ( > http://docs.basho.com/riak/1.4.9/ops/building/planning/cluster/#Ring-Size-Number-of-Partitions > ) > > > > “The default number of partitions in a Riak cluster is 64. This works for > smaller clusters, but if you plan to grow your cluster past 5 nodes it is > recommended you consider a larger ring size.” > > > > In our staging and production environments we have 5 nodes, and this will > likely grow, so we chose a ring assize of 128. We like to keep the same > config across all out environments where possible, so we replicated this in > the 3-node test environment. > > > > There is nothing in this document to suggest a upper limit on ring size > based on number of nodes (or capacity of individual nodes). From where in > the Riak docs is this spreadsheet referenced? > > > > I can rebuild the cluster with ring size 16 if necessary, but can you > explain why the current larger ring size produces the sudden memory spike > and subsequent crash? > > > > Thanks, > > > Simon. > > > > *From:* Ciprian Manea [mailto:cipr...@basho.com] > *Sent:* 12 February 2015 11:26 > *To:* Simon Hartley > *Cc:* riak-users@lists.basho.com > *Subject:* Re: Simple 3 node test cluster eating all my memory > > > > Hi Simon, > > > > Looking at this problem from another angle, a ring size of 128 is too > large for just 3 servers with 4 GB RAM each. For instance when dimensioning > a cluster with LevelDB backend we recommend our customers to observe the > calculations on this spreadsheet [0]. > > > > Filling the above spreadsheet with your system's details (3 nodes, 4 GB > RAM) we get a ring-size of 16 for the riak cluster. Would you be able to > recreate the cluster with ring-size 16 and test again? > > > > [0] > https://docs.google.com/spreadsheet/ccc?key=0AnW_U8Qe8NdYdGk2V3Qza0VRNkxyRFNGUVVCV0c3V3c&usp=sharing#gid=0 > > > > > > Thanks, > > Ciprian > > > > On Thu, Feb 12, 2015 at 11:51 AM, Simon Hartley < > simon.hart...@williamhill.com> wrote: > > Hi, > > > > We have a simple 3 node test cluster, and we are seeing this cluster > fall-over under quite modest loads, 2-3 times a day with the node reporting > out of memory problems. > > > > Our basic details are: > > > > · Riak 1.4.9 > > · 3 nodes, each being: > > o A virtual RedHat EL > > o 2 x 2.2GHz CPU > > o 4GB RAM > > · In-memory back end > > · 128 segment ring > > > > We have tried to limit the in-memory max memory by the following setting > in app.config: > > > > %% Memory Config > > {memory_backend, [ > > {max_memory, 32}, %% 32 megabytes > > {ttl, 86400} %% 1 Day in seconds > > ]}, > > > > The behaviour we are seeing is a sudden and rapid increase in memory > allocated to riak, up to 100% available RAM, and then a crash. > > > > This is happening on all 3 nodes (at different times). > > > > When looking through the console.log just prior to the out of memory / > crash we see log entries similar to the following appearing: > > > > 2015-02-11 16:50:27.356 [info] > <0.98.0>@riak_core_sysmon_handler:handle_event:92 monitor large_heap > <0.238.0> > [{name,riak_core_gossip},{initial_call,{riak_core_gossip,init,1}},{almost_current_function,{riak_core_gossip,update_gossip_vers > > ion,1}},{message_queue_len,78}] > [{old_heap_block_size,0},{heap_block_size,47828850},{mbuf_size,0},{stack_size,15},{old_heap_size,0},{heap_size,13944475}] > > > > We can’t see any errors at the appropriate times in the error.log > > > > We see the following in erlang.log.1: > > > > ===== ALIVE Wed Feb 11 17:00:24 GMT 2015 > > /usr/lib64/riak/lib/os_mon-2.2.9/priv/bin/memsup: Erlang has closed. > > Erlang has closed > > > > Crash dump was written to: /var/log/riak/erl_crash.dump > > eheap_alloc: Cannot allocate 4454408120 bytes of memory > > > > ===== > > > > Anyone any ideas? > > > > *Simon Hartley* > > Solutions Architect > > > > Email: simon.hart...@williamhill.com > > Skype: *+44 (0)113 397 6747 <%2B44%20%280%29113%20397%206747>* > > Skype: *sijomons* > > > > *William Hill Online*, St. Johns, Merrion St. Leeds, LS2 8LQ > > [image: Description: Description: Description: > cid:image002.png@01CC2FFA.24244CF0] > > > > Confidentiality: The contents of this e-mail and any attachments > transmitted with it are intended to be confidential to the intended > recipient; and may be privileged or otherwise protected from disclosure. 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Each of > WHG (International) Limited and WHG Trading Limited is registered in > Gibraltar and has its registered office at 6/1 Waterport Place, Gibraltar. > Unless specifically indicated otherwise, the contents of this e-mail are > subject to contract; and are not an official statement, and do not > necessarily represent the views, of William Hill PLC, its subsidiaries or > affiliated companies. Please note that neither William Hill PLC, nor its > subsidiaries and affiliated companies can accept any responsibility for any > viruses contained within this e-mail and it is your responsibility to scan > any emails and their attachments. William Hill PLC, its subsidiaries and > affiliated companies may monitor e-mail traffic data and also the content > of e-mails for effective operation of the e-mail system, or for security, > purposes.. >
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