The volume.config file enables you to manage your cache space more efficiently and restrict disk usage by creating cache volumes of different sizes for specific protocols. You can further configure these volumes to store data from certain origin servers and/or domains in the hosting.config file.


The volume configuration must be the same on all nodes in a cluster. You must stop Traffic Server before you change the cache volume size and protocol assignment. For step-by-step instructions about partitioning the cache, refer to Partitioning the Cache.


For each volume you want to create, enter a line with the following format:

volume=volume_number  scheme=protocol_type  size=volume_size

where volume_number is a number between 1 and 255 (the maximum number of volumes is 255) and protocol_type is http. Traffic Server supports http for HTTP volume types; volume_size is the amount of cache space allocated to the volume. This value can be either a percentage of the total cache space or an absolute value. The absolute value must be a multiple of 128 MB, where 128 MB is the smallest value. If you specify a percentage, then the size is rounded down to the closest multiple of 128 MB.

Each volume is striped across several disks to achieve parallel I/O. For example: if there are four disks, then a 1-GB volume will have 256 MB on each disk (assuming each disk has enough free space available). If you do not allocate all the disk space in the cache, then the extra disk space is not used. You can use the extra space later to create new volumes without deleting and clearing the existing volumes.


The following example partitions the cache evenly between HTTP and HTTPS requests:

volume=1 scheme=http size=50%
volume=2 scheme=http size=50%