Cassandra attempts to lock the heap at startup, but all the memory allocated after startup is not locked. So you do want to make sure the allowed locked memory is large.
Disabling or vastly dialing down swappiness is a best practice for all server software, not just Cassandra, so you should still at the very least set the swappiness to some small number of you don’t want to completely disable it. -Jeremiah > On Apr 16, 2020, at 5:57 PM, Nitan Kainth <nitankai...@gmail.com> wrote: > > Swap is controlled by OS and will use it when running short of memory. I > don’t think you can disable at Cassandra level > > > Regards, > Nitan > Cell: 510 449 9629 > >>> On Apr 16, 2020, at 5:50 PM, Kunal <kunal.v...@gmail.com> wrote: >>> >> >> Hello, >> >> I need some suggestion from you all. I am new to Cassandra and was reading >> Cassandra best practices. On one document, it was mentioned that Cassandra >> should not be using swap, it degrades the performance. >> My question is instead of disabling swap system wide, can we force Cassandra >> not to use swap? Some documentation suggests to use memory_locking_policy in >> cassandra.yaml. >> >> How do I check if our Cassandra already has this parameter and still uses >> swap ? Is there any way i can check this. I already checked cassandra.yaml >> and dont see this parameter. Is there any other place i can check and >> confirm? >> >> Also, Can I set memlock parameter to unlimited (64kB default), so entire >> Heap (Xms = Xmx) can be locked at node startup ? Will that help? >> >> Or if you have any other suggestions, please let me know. >> >> >> Regards, >> Kunal >>
