# Storage Resource Management

The challenge for Storage Resource Management (SRM) vendors is to present a unified picture of the unified storage platform.

A few things should be mentioned to SRM developers who are unfamiliar with the implications of the WAFL file system design. Following are a few points:

- Deleting files does not immediately free the underlying storage unless they are deleted before a Snapshot copy is taken. After the blocks are in a Snapshot copy, the storage system stays used until the Snapshot copy is old or is deleted manually.
- The Unified Storage Device (USD) exists on multiple levels of a traditional architectural diagram. On the one hand, it serves raw disk access through LUNs. On the other hand, it serves files. This is part of the problem pointed to just above.
- NetApp occasionally gets requests for doing file walking within the file system for performance reasons. An API for this purpose is under development.

This preceding diagram of simplified Unified Modelling Language shows the principal USD components as they relate to each other. In versions of Data ONTAP prior to 7.0, the aggregate and volume/file system elements were effectively merged.

Related Topics

- Hardware

- WAFL, Snapshot copies, and derivative software

- WAFL Storage Hierarchy

- RAID 4 and RAID 6

- Networking and Clustering

- Networking Configurations

- MultiStore

- File Sharing

- Protocols

- Unified Storage

- Multiprotocol File Permissions

- Developing applications that talk to Unified Storage Devices