Index_D

D

DAO. See Data Access Objects (DAO)

Data Access Objects (DAO)

example pattern implementation, 422

function of in object-oriented design, 421 “423

using for data tier general database access, 409

data redundancy

understanding, 37

Data Replication Service (DRS)

provided by WebSphere 5, 63

data source

defined, 193

data source provider

queue modeling item to monitor, 284

data sources

as components of a WebSphere queue, 280

data stores and repositories

in WebSphere 5, 77 “78

data tier

importance of releasing JDBC resources when finished with them, 407 “408

performance in a WebSphere environment, 406 “409

using prepared SQL statements where possible in, 409

using WebSphere data sources in, 407

data types

in a WebSphere environment, 272 “273

database

as component of a WebSphere queue, 280

overview, 411 “412

database and other external interface pooling

in multiple JVMs with multiapplication servers, 215 “217

database availability options

database replication, 306

database server clustering, 305

in database server tier, 305 “306

hot-standby databases, 306

stand-alone database instances, 305

database connection script

using to plot database connection usage, 248

database datasource

effect on performance, 8

database errors

handling in application code, 361 “362

database failover events

summarizing, 369 “370

database platform

determining scalability needed for, 430 “431

Oracle and DB2 monitoring tools, 441 “442

database replication

database availability options, 306

in geographically distributed technologies, 226 “227

database server clustering, 294

database availability option, 305

database server failover

considerations when using Oracle 8 i OPS, 9 i OPS, and 9 i RAC, 365 “369

in WebSphere applications, 356 “370

database server node

recommendation for WebSphere-to-database networking, 144

database servers

having multiple for redundancy or high availability, 363 “364

database server software

in single-channel topologies, 175 “176

database server tier

database availability options in, 305 “306

in JDBC type 3 driver implementation, 425

database tiers

topological considerations important to, 218 “223

database transactional performance

determining cause of poor, 499

database transaction load

considerations, 180 “183

database workloads

most common flavors of, 434

databases

code example showing proper object closure, 420 “421

data layout and design, 435

determining your reliance on, 430

effect on performance, 8

factors to consider when implementing, 429 “431

key items to consider when implementing high end, 432

db_block_buffers/ parameter

for Oracle system configuration and tuning, 437

db_block_size parameter

for Oracle system configuration and tuning, 437

db_cache_size parameter

for Oracle system configuration and tuning, 437

DB2. See IBM DB2

Decision Support System (DSS) workload

CPU availability needed for, 433

workload summary matrix for, 434

delay acknowledgment

settings in IBM AIX, 268

delay acknowledgment ports

setting in IBM AIX, 269

deployment descriptor

for your J2EE application, 372

Deployment Manager

function of in WebSphere 5, 73, 202, 306

design considerations

for legacy systems integration, 455 “472

Direct Attached Storage (DAS) devices

function of, 128

directional flow rule

used by the Mirrored Waterfall Performance Methodology, 27 “30

disaster recovery

typical configuration and function of, 299 “301

disaster recovery solution

implementing, 300 “301

disk

I/O monitoring, 485 “490

performance in Windows NT/2000/XP, 488 “490

telltale signs of high disk utilization, 488

disk I/O performance

calculating disk transfer time, 134 “135

disk layout approaches

in system and hardware tuning and optimization, 272 “275

for Unix file systems, 273 “275

disk performance

the true effects of striping disks, 136 “137

disk speed

effect of in a WebSphere environment, 130 “131

disk storage technologies

costs associated with, 137 “140

current and future performance overview, 131

effect of disk speed in a WebSphere environment, 130 “131

implementation costs, 138 “139

importance of architectural complexity in selecting, 140

management and support costs, 138

overall performance, 131 “137

questions to ask for choosing the right architecture, 132 “133

summary, 140

upgrade and scalability costs, 140

disk systems

comparing, 120 “130

disk technologies

comparing, 120 “130

% Disk Time

graphing for a Windows XP-based server, 489 “490

disks and disk configuration

database-specific considerations for, 432

distributed storage architecture

example of, 128

DLPAR. See dynamic logical partitioning (DLPAR)

DMZ firewall

function of, 353 “354

doGet() method

importance of questioning the use of, 399

domain vs. WebSphere 5 cell , 70

domains

using with SunFire range of servers, 107

doPost() method

importance of questioning the use of, 399

DoS attacks

mitigating chances of with separate network, 351

downtime

calculating the cost of, 45 “46

causes of, 41 “42

costs of to various industries, 43

example cost impact factors, 45

DSS workload. See Decision Support System (DSS) workload

dual application server configuration

example of in WebSphere, 313

dual Web server

single application server topology, 190 “197

thick model example, 191

thin model example, 190

dual Web server, single application server topology

advantages of, 195 “196

common uses for, 190 “197

disadvantages of, 196 “197

final considerations for using, 197

dual-channel topologies vs. single-channel topologies, 174

dual-CPU configuration

UltraSPARC III CPU connections to, 101

Duration value

in Performance tool network utilization output, 496

Duron processor

function of, 87

dynamic logical partitioning (DLPAR)

in IBM PowerPC platform (pSeries), 147

Dynamic System Domains (DSDs)

function of in Sun SPARC platform, 145 “146