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For information about selecting hardware, see httphttps://cassandra.apache.org/doc/latest/cassandra/managing/operating/hardware.html.

In order to To achieve adequate performance, create separate partitions, ideally , on separate drives. This helps to avoid iI/o contentionO contention.  We recommend 3 separate block devices (disks). The We recommend 3 separate storage devices or at least 3 separate partitions for non-production environments:

1. /opt/local (the first block device should contain the operating system as well as a mount for the programs

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1. ).

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2. The second block device (

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1. NVMe/SSD) should contain a mount point at /data (the device must have high storage capacity for all the data).

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2. The third block

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1. device (

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1. NVMe/SSD, but does not need to be of high capacity) should contain a mount point at /logs.

If you use SSD, the device can be a partition on the same block device as the /data partition.  All All partitions should be formatted using the XFS file system, and there should not be a swap partition. The /backup partition can be a mount on a shared storage device but should not be on the same physical drive as the /data partition.

See an example of the contents of /etc/fstab after partitioning where the partitions were created using LVM (without a mount for the /backup partition).

#
# /etc/fstab
# Created by anaconda on Tue May  2 16:31:05 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/cl_twccentos7-root /                       xfs     defaults        0 0
/dev/mapper/cl_twccentos7-data /data                   xfs     defaults        0 0
/dev/mapper/cl_twccentos7-logs /logs                   xfs     defaults        0 0
/dev/mapper/cl_twccentos7-opt_local /opt/local         xfs     defaults        0 0

In the above example:

• Disk 1 contains the following partitions:  /opt/local (40GB) and / (rest of the drive capacity).
• Disk 2 (the disk with the highest capacity) contains the /data partition (at least 250GB). Due to the way compactions are handled by Cassandra, up to 50% of headroom may be needed in a worst-case scenario.
• Disk 3 contains the /logs partition (at least 10 GB).
• You should also create an additional mount for backups. Unlike the data and commit log partitions, which should be on SSD storage, this mount can be of any type (including centralized storage such as a SAN or NAS). It should have at least the same capacity as the /data partition.

The partitioning scheme above is an example. Internal security protocols in your organization may dictate that other directories may not be located in the main partition. During the installation, all applications will be installed in /opt/local. By default, Cassandra will be installed install in /var/lib. Application logs will be written to /home/twcloud.