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From Thomas Julian <>
Subject Optimal value for concurrent_reads for a single NVMe Disk
Date Tue, 20 Sep 2016 10:11:00 GMT

We are using Cassandra 2.1.13 with each node having a NVMe disk with the configuration of
Total Capacity - 1.2TB, Alloted Capacity -  880GB. We would like to increase the default value
of 32 for the param concurrent_reads. But the document says 

"(Default: 32)note For workloads with more data than can fit in memory, the bottleneck is
reads fetching data from disk. Setting to (16 × number_of_drives) allows operations to queue
low enough in the stack so that the OS and drives can reorder them. The default setting applies
to both logical volume managed (LVM) and RAID drives."

According to this hardware specification, what could be the optimal value that can be set
for concurrent_reads?

Best Regards,


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