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Improved
Storage Management for Central Servers
By
John Chan
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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 |
