Do Storage Management
the DBA deals with database management systems that
store data, a good part of the DBA's job will involve
planning for the actual storage of database data. As a
rule, DBMS vendors do not certify or explicitly
support any specific third party storage products.
Instead, the assumption is made that some underlying
storage technology is available and will be reliable.
The DBA must evaluate the many products, technologies,
and vendors that provide storage solutions to
determine what will work best with each DBMS.
Fortunately, most storage technologies can work with
most DBMS products. The predominant storage technology
used for data management is the disk drive. Modern
disk drives are more reliable than in years past with
an ever-increasing Mean Time Before Failure (MTBF). It
is not unheard of for disk drives to achieve in excess
of 100,000 hours of availability before failing. But
the mechanical nature of the disk drive renders them
more vulnerable to failure than other computer
component. As the number of disk drives in a system
increases the vulnerability increases. Certain modern
storage solutions, such as RAID, can be used to
address some of the MTBF problems.
mission critical applications, data integrity can be
more important than data availability. If the storage
media is unreliable and a failure causes data
corruption, the lost data can be more of a problem
than the downtime. It is imperative that database
storage solutions protect the data.
performance is I/O dependent - the faster the DBMS can
complete an I/O operation the faster the database
application will run. Remember that data retrieval
from storage media takes much longer to complete than
data retrieval from cache or memory. For this reason,
some modern storage systems provide their own caching
mechanism to pre-stage data in memory - thereby
reducing the wait time associated with traditional
disk I/O operations.
storage is becoming more central to business
operations. Heterogeneous, multi-terabyte, database
sites are not uncommon these days. The amount of data
being stored is greater than ever before, and data is
being stored for longer durations, too. One company,
Winter Corp., specializes in VLDB (Very Large
Database) issues. In its most recent survey of the
largest databases in the world Winter Corp. projects a
100 TB database by 2005. Additionally, the report
documents several very large databases including a
10.5 TB Unix-based data warehouse and a 1.45 TB
Windows NT-based data warehouse.
the DBA, this growth in storage capacity further
increases the complexity of managing data and
databases. Many organizations are implementing new
storage technologies, such as Network Attached Storage
(NAS) and Storage Area Networks (SANs), to help manage
the ever-increasing amount of storage required for
modern applications. Goals to consider while building
a storage system for your database include: preventing
loss of data; assuring that adequate capacity is
available and that the storage solution can easily
scale as storage needs grow; selecting a solution that
provides fast access to data with minimal, or no
interruptions to service; choosing storage solutions
that are fault-tolerant and that can be repaired
rapidly when a failure occurs; selecting a storage
solution where you can add or replace disks without
taking an outage; and combining all of the above into
a cost-effective storage solution that is within a
budget your company can afford.
the DBA and the storage administrator will need to
cooperate to facilitate proper database storage.
Indexing, partitioning, clustering, and separation of
data will cause the database to require more storage
(and across more drives) than most storage
administrators anticipate. The DBA will need to
clearly explain how much storage is required for the
database. The better the DBA communicates, and the
better the relationship is between these two IT
professionals, the better your database applications
will perform. And that is what it is all really about.