Physical Volume Library deadlock avoidance in a striped media environment
- IBM Government System, Houston, Texas (United States)
- Lawrence Livermore National Lab., CA (United States)
Most modern high performance storage systems store data in large repositories of removable media volumes. Management of the removable volumes is performed by a software module known as a Physical Volume Library (PVL). To meet performance and scalability requirements, a PVL may be asked to mount multiple removable media volumes for use by a single client for parallel data transfer. Mounting sets of volumes creates an environment in which it impossible for multiple client requests to deadlock while attempting to gain access to storage resources. Scenarios leading to deadlock in a PVL include multiple client requests that contend for the same cartridge(s), and client requests that vie for a limited set of drive resources. These deadlock scenarios are further complicated by the potential for out-of-order volumes to be mounted (for example, by Automatic Cartridge Loaders or human operators). This paper begins by introducing those PVL requirements Which create the possibility of deadlock. Next we examine traditional approaches to deadlock resolution and how they might be applied in a PVL. This leads to a design for a PVL which addresses deadlock scenarios. Following the design presentation is a discussion of possible design enhancements. We end with a case study of an actual implementation of the PVL design in the High Performance Storage System (HPSS).
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 114668
- Report Number(s):
- UCRL-JC--20441; CONF-950985--5; ON: DE96001315
- Country of Publication:
- United States
- Language:
- English
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