Storage Use Optimization¶
This section discusses best practices for minimizing the space needed to store your Pachyderm data, increasing the performance of your data processing as related to data organization, and general good ideas when you are using Pachyderm to version/process your data.
When a file, commit, repo is deleted, the data is not immediately removed from the underlying storage system, such as S3, for performance and architectural reasons. This is similar to how when you delete a file on your computer, the file is not necessarily wiped from disk immediately.
To actually remove the data, you may need to manually invoke garbage collection. The easiest way to do it is through
pachctl garbage-collect. You can start
pachctl garbage-collect only when no active jobs are running. Also, you need to ensure that all
pachctl put file operations have been completed. Garbage collection puts the cluster into a read-only mode where no new jobs can be created and no data can be added.
Setting a root volume size¶
When planning and configuring your Pachyderm deployment, you need to make sure that each node's root volume is big enough to accommodate your total processing bandwidth. Specifically, you should calculate the bandwidth for your expected running jobs as follows:
(storage needed per datum) x (number of datums being processed simultaneously) / (number of nodes)
Here, the storage needed per datum must be the storage needed for the largest datum you expect to process anywhere on your DAG plus the size of the output files that will be written for that datum. If your root volume size is not large enough, pipelines might fail when downloading the input. The pod would get evicted and rescheduled to a different node, where the same thing might happen (assuming that node had a similar volume).