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
>>>>>>
>>>>>

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