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
>>>>
>>>

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