Database Reference
In-Depth Information
Optimizing user limits
The
limits.conf
file (located at
/etc/security/
) gives a simple mechanism to set
resource limits to users. To make Cassandra work without choking, it must be provided
with higher resource availability, which can be easily done by this file. Add or update the
following values to various resources (you need to have root access to do this):
* softnofile 32768
* hard nofile 32768
root soft nofile 32768
root hard nofile 32768
* softmemlock unlimited
* hard memlock unlimited
root soft memlock unlimited
root hard memlock unlimited
* soft as unlimited
* hard as unlimited
root soft as unlimited
root hard as unlimited
If you are using a cloud, you may want to set and store the values mentioned in the follow-
ing list to your machine image file:
•
nofile
: By default, a Linux-based system has an upper cap on the number of
open files. This may cause trouble for a moderately large setup. Reading and/or
writing may involve a large number of file accesses. Apart from this, node-to-node
communication is socket-based, that is, it takes one file descriptor per socket.
Thus, having a setting that allows a high number of concurrently open file
descriptors is a good idea.
A file descriptor can be anything below 2
20
for RHEL and family. 32768 (= 2
15
) is
a good range of values to start with.
•
memlock
: If you are coming from a relational database background,
memlock
is
chiefly used for a huge page. The
memlock
parameter specifies how much
memory any
* = wild card
user can lock in its address space. It can be set to
unlimited or the maximum value of RAM in KB.
The rest of the settings in the preceding configuration are just for hard and soft limits. In
