/volatile disk pool

Each experiment or group is assigned a quota and reservation. Quota is a soft limit,  meaning that when the usage exceeds the quota, the user can still write additional data, but within the next few hours the oldest files will be deleted to return the project to it's quota.  Quota is oversubscribed (meaning the sum of the quotas exceeds the available space), and so sometimes files must be deleted even below a group's quota.  Reservation is the guaranteed space for the group.

The Scicomp Web portal is the best resource to check the volatile disk pool allocation and usage. The jvolatile utility provides a tool for users to query the volatile usage in a script.

Deletion Policy: The /volatile area is managed by a process that cleans up the area periodically in multiple steps listed below. The first two steps will always take place. Third and forth steps will be proceed if the total usage of the area still does not meet the target.

  1. All files that have not been used for more than 6 months will be deleted.
  2. If a project exceeds its quota, the least-recently-used (LRU) files will be deleted until the total usage of the project is below its quota.
  3. Each file is assigned a deletion index that combines the excess usage of a project over its reservation coupled with the period of time the file is been modified. Files will be deleted according to the index in a descending order until the total /volatile usage is below its overall target.
  4. When Lustre total usage is reached to a critical point, additional file deletion will be performed (using file deletion index).