Direct Attached Storage (DAS)

Upon completion of this lesson, you will be able to:

•Discuss the benefits of DAS

•Describe the elements of DAS

•Discuss DAS management considerations

•Discuss DAS challenges

What is DAS?

Internal Direct Connect

 
• Uses block level protocol for data access





DAS Benefits


• Ideal for local data provisioning

• Quick deployment for small environments

• Simple to deploy

• Reliability

• Low capital expense

• Low complexity

DAS Connectivity Options

• ATA (IDE) and SATA

– Primarily for internal bus

• SCSI

– Parallel (primarily for internal bus)

– Serial (external bus)

• FC

– High speed network technology

• Buss and Tag

– Primarily for external mainframe

– Precursor to ESCON and FICON

DAS Management

• Internal

– Host provides:

•Disk partitioning (Volume management)

•File system layout

– Direct Attached Storage managed individually through the server and the OS

• External

– Array based management

– Lower TCO for managing data and storage Infrastructure

DAS Challenges

• Scalability is limited

– Number of connectivity ports to hosts

– Number of addressable disks

– Distance limitations

• Downtime required for maintenance with internal DAS

• Limited ability to share resources

– Array front-end port

– storage capacity

Resulting in islands of over and under utilized storage pools