Improved Storage Management for Central Servers

by John Chan

Today, servers across the LANs/WANs need to provide fast, reliable, ubiquitous access to data as required by various applications. In particular, mission-critical applications require data storage that can be operational all year round as well as can be expanded easily without interrupting any application currently running. At present, all server data is stored in the direct attached storage. To manage effectively the vast amount of data volume scattered among the some 50 central servers poses a great challenge to the Computing Services Centre (CSC). In view of such a problem and its consequence of possible risks to the total network performance, the CSC has recently adopted the Network Storage System (NSS) as the standard platform for central storage. Based on the requirement of high availability and disaster recovery, the backup, the data sharing, management, and future expansion, the Storage Area Network (SAN) is chosen as the NSS architecture for deployment.

Benefits of SAN

1. Storage Provision
SAN has the ability to create a pool of storage that can be dynamically allocated and de-allocated by different servers. General users can now have more storage to use and resources can be rapidly and dynamically adjusted as required.

2. High Availability
SAN has the ability to make any-to-any connections among multiple servers and storage devices. They can create a shared pool of storage that can be accessed by multiple servers through multiple paths, resulting in high availability.

3. Data Sharing
SAN allows multiple distributed servers to concurrently access a centralised storage for data sharing applications. This is especially useful for deploying more servers to handle those mission-critical applications during short peak usage periods, such as the summer student registration.

4. Management and Future Expansion
Storage devices are distributed through a network and managed from a central point through a single management tool. This will lower the cost of storage management and standardise the control of the administrator, hence providing better reliability and availability. New devices can also be added on-line without disrupting data access.

The Solution

The solution proposed by EMC Computer Systems Ltd. was recommended and acquired by the CSC in January 2001. By the end of February, all of the necessary hardware and software were delivered, and the CSC and the EMC have been jointly working together since then on the implementation of the system.

The EMC solution consists of a Symmetrix 8730 Frame as the main storage base and Brocade switches and Fibre Channel cables are used for setting up the SAN network framework. Most of the to-be-connected servers will be using Fibre Channel cables for faster access. Some, which do not support Fibre Channel at this moment, will use Ultra SCSI for the connection. The initial configuration has around 2.7 TB of mirrored storage and 0.65 TB of raw storage for all to-be-connected servers. This kind of raw storage can be used for data snapshot in which a mirror image of active production volume can be created at any point of time. This is extremely useful in facilitating disk volume backup as well as creating a testing environment for application development while providing the normal production service.

The EMC solution provides the best and properly balanced set-up with no performance bottleneck on any part of the SAN network. It also supports all the different kinds of computer platforms with no significant modification required and no negative performance impact on the to-be-connected servers.

Implementation Schedule

Once the framework has been installed, the SAN storage will be ready for deployment on all to-be-connected servers. Existing data on these servers will be migrated to this new storage by phase, and the tentative schedule is depicted as follows:

Services Implemented storage Expected date of completion
Central Servers for Departmental LAN 400 GB End of August 2001
General Unix Server and Personal Web Server 600 GB End of July 2001
High-performance Computing Unix Server 300 GB End of June 2001
Staff E-mail Server 400 GB End of August 2001
Student E-mail Server 300 GB End of July 2001
WebCT Server 240 GB End of June 2001
Intranet Database Server 200 GB End of July 2001
Banner Information Database Server 180 GB End of October 2001