Qumulo’s Distributed File System
Contents of this guide (old table of contents)
Just as real-time aggregation of metadata enables Qumulo’s real-time analytics, it also enables real-time capacity quotas.
Quotas allow admins to specify how much capacity a given directory is allowed to use for files. For example, if an admin sees that a rogue user is causing a sub-directory to grow too quickly, the admin can instantly limit the capacity of that user’s directory.
In Qumulo’s file system, quotas are deployed immediately, and do not have to be provisioned. They are enforced in real-time and changes to their capacities are immediately implemented. A side benefit is that quotas assigned to directories move with them and directories themselves can be moved into and out of quota domains.
Unlike some other systems, Qumulo quotas do not require breaking the file system into volumes.
Also, with Qumulo, moving a quota, or moving directories across quota domains, involves no lengthy tree walks, job scheduling or cumbersome, multi-step processes. Quotas can be applied to any directory, even nested ones. If an allocation has more than one quota because of nested directories, all quotas must be satisfied in order to allocate the requested space.
Because quota limits are recorded as metadata at the directory level, quotas can be specified at any level of the directory tree. When a write operation occurs, all relevant quotas must be satisfied. These are hard limits.
The precision and agility of Qumulo’s real-time quotas are possible because the built-in aggregator continually keeps the summary of the total amount of storage used per directory up to date.