The Content Software for File system includes user-defined policies that serve as guidelines to control data storage management. They are derived from several factors:
- The rate at which data is written to the system and the quantity of data.
- The capacity of the SSDs configured to the Content Software for File system.
- The network speed between the Content Software for File system and the object store,and its performance capabilities, for example, how much the object store can contain.
Filesystem groups are used to define these policies, while a filesystem is placed in a filesystem group according to the desired policy if the filesystem is tiered.
For tiered filesystems, define the following parameters per filesystem:
- The size of the filesystem.
- The amount of filesystem data to be stored on the SSD.
Define the following parameters per filesystem group:
- The Drive Retention Period Policy is a time-based policy which is the target time for data to be stored on an SSD after creation, modification or access, and before release from the SSD, even if it is already tiered to the object store, for metadata processing and SSD caching purposes (this is only a target; the actual release schedule depends on the amount of available space).
- The Tiering Cue Policy is a time-based policy that determines the minimum time that data remains on an SSD before it is considered for release to the object store. As a rule of thumb, this must be configured to a third of the Retention Period, and in most cases, this works well. The Tiering Cue is important because it is pointless to tier a file which is about to be modified or deleted from the object store.
Example:
When writing log files which are processed every month but retained forever, it is recommended to define a Retention Period of 1 month, a Tiering Cue of 1 day, and ensure that there is sufficient SSD capacity to hold 1 month of log files.
When storing genomic data which is frequently accessed during the first 3 months after creation, requires a scratch space for 6 hours of processing, and requires output to be retained forever: It is recommended to define a Retention Period of 3 months and to allocate an SSD capacity that will be sufficient for 3 months of output data and the scratch space. The Tiering Cue should be defined as 1 day, in order to avoid a situation where the scratch space data is tiered to an object store and released from the SSD immediately afterwards.