Thank you On Thu, Apr 15, 2021 at 7:20 PM Kane Wilson <k...@raft.so> wrote:
> Yes that warning will still appear because it's a startup check and > doesn't take into account the disk_access_mode setting. > > You may be able to cope with just indexes. Note this is still not an ideal > solution as you won't be making full use of your available memory. > > raft.so - Cassandra consulting, support, and managed services > > > On Fri, Apr 16, 2021 at 10:10 AM Jai Bheemsen Rao Dhanwada < > jaibheem...@gmail.com> wrote: > >> Also, >> >> I just restarted my Cassandra process by setting "disk_access_mode: >> mmap_index_only" and I still see the same WARN message, I believe it's >> just a startup check and doesn't rely on the disk_access_mode value >> >> WARN [main] 2021-04-16 00:08:00,088 StartupChecks.java:311 - Maximum >>> number of memory map areas per process (vm.max_map_count) 65530 is too low, >>> recommended value: 1048575, you can change it with sysctl. >> >> >> On Thu, Apr 15, 2021 at 4:45 PM Jai Bheemsen Rao Dhanwada < >> jaibheem...@gmail.com> wrote: >> >>> Thank you Kane and Jeff. >>> >>> can I survive with a low mmap value of 65530 with "disk_acces_mode = >>> mmap_index_only" ? does this hold true even for higher workloads with >>> larger datasets like ~1TB per node? >>> >>> On Thu, Apr 15, 2021 at 4:43 PM Jeff Jirsa <jji...@gmail.com> wrote: >>> >>>> disk_acces_mode = mmap_index_only to use fewer maps (or disable it >>>> entirely as appropriate). >>>> >>>> >>>> >>>> On Thu, Apr 15, 2021 at 4:42 PM Kane Wilson <k...@raft.so> wrote: >>>> >>>>> Cassandra mmaps SSTables into memory, of which there can be many files >>>>> (including all their indexes and what not). Typically it'll do so greedily >>>>> until you run out of RAM. 65k map areas tends to be quite low and can >>>>> easily be exceeded - you'd likely need very low density nodes to avoid >>>>> going over 65k, and thus you'd require lots of nodes (making management >>>>> harder). I'd recommend figuring out a way to up your limits as the first >>>>> course of action. >>>>> >>>>> raft.so - Cassandra consulting, support, and managed services >>>>> >>>>> >>>>> On Fri, Apr 16, 2021 at 4:29 AM Jai Bheemsen Rao Dhanwada < >>>>> jaibheem...@gmail.com> wrote: >>>>> >>>>>> Hello All, >>>>>> >>>>>> The recommended settings for Cassandra suggests to have a higher >>>>>> value for vm.max_map_count than the default 65530 >>>>>> >>>>>> WARN [main] 2021-04-14 19:10:52,528 StartupChecks.java:311 - Maximum >>>>>>> number of memory map areas per process (vm.max_map_count) 65530 is >>>>>>> too low, recommended value: 1048575, you can change it with sysctl. >>>>>> >>>>>> >>>>>> However, I am running Cassandra process as a container, where I don't >>>>>> have access to change the value on Kubernetes worker node and the >>>>>> cassandra >>>>>> pod runs with less privileges. I would like to understand why Cassandra >>>>>> needs a higher value of memory map? and is there a way to restrict >>>>>> Cassandra to not use beyond the default value of 65530. If there is a way >>>>>> please let me know how to restrict and also any side effects in making >>>>>> that >>>>>> change? >>>>>> >>>>>> Thanks in advance >>>>>> >>>>>
