HPSS Introduction

General

The High Performance Storage System HPSS is developped by several Labs in the US in cooperation with IBM. HPSS is a Hierarchical Storage Management System (HSM) and it is developped to manage petabytes of data stored on disks and in tape libraries.

HPSS at HLRS manages 288 TB of disk storage and more than a petabyte tape storage.

Usage

For the user, there are currently two ways to access the HPSS environment to store data: ftp and parallel ftp. More information about this is given in the User Access section. Please remember always, that your data is stored on tape and might be on disk. Especially, if you have not touched your data for a longer time, it will happen that your data is located on tape only. This may result in some latency at the begin of data transfers when reading data.

Class of Service

The only control instrument visible to the outside is the class of service (cos). Each class of service has an id which is used to specify the class of service to be used. The current setup knows three class of service for general usage with different chracteristics.

cos 112 is for files sized smaller than 2 GB

cos 122 is for files larger than 2 GB but small than 8 GB

cos 132 is for files larger than 8 GB

Depending on the class of service, the internal handling of files is different. Please find more information about this in the chapter Configuration Details below.

Hardware

In the HPSSSc omplex, 10 server PC's are working as metadata server and data movers. Each system is equipped with 8 CPU cores on 4 sockets using 16 GB or 32 GB of main memory. Additinally, each systems has 10 GBit Ethernet, Infiniband and Fibre Channel adapters.

Software

We are using the current version of HPSS (High Performance Storage System) distributed by IBM. HPSS is a Hierarchical Storage Management System (HSM) which is able to manage Petabytes of data on disk and tape storage.

Configuration Details

Here are some configuration details, which are interesting for the users to know.

In our environment, we support three classes of service. Each one is planned for a different file size. The internal handling of the data is different depending on the class of service the file belongs to. Independent of the used class of service, each file will be written to tape. For safety reasons, two copies of each file are written to different tape cartridges.

The three different classes of service are:

112

Filesize: size < 2GB

Temporary Disk Storage: file is written to one RAID Volume

Tape 1st copy: one tape

Tape 2nd copy: a second tape

122

Filesize: 2GB < size < 8GB

Temporary Disk Storage: file is striped over 4 RAID Volumes

Tape 1st copy: one tape

Tape 2nd copy: a second tape

132

Filesize: size > 8GB

Temporary Disk Storage: file is striped over 4 RAID Volumes

Tape 1st copy: striped over 4 tape cartridges

Tape 2nd copy: a different tape cartridge