IBM TS2340 User Guide - Page 34

Dynamic Load Balancing, Supported Devices and Feature Codes

Page 34 highlights

Path Failover Dynamic Load Balancing The dynamic load balancing support optimizes resources for tape devices that have physical connections to multiple Host Bus Adapters (HBA) in the same machine. When an application opens a device that has multiple HBA paths configured, the device driver determines which path has the HBA with the lowest usage, and assigns that path to the application. When another application opens a different device with multiple HBA paths, the device driver again determines the path with the lowest HBA usage and assigns that path to the second application. The device driver updates the usage on the HBA assigned to the application when the device is closed. Dynamic load balancing uses all Host Bus Adapters whenever possible and balance the load between them to optimize the resources in the machine. For example, consider a machine with two Host Bus Adapters, HBA1 and HBA2, with multiple tape drives attached. Each tape drive is connected to both HBA1 and HBA2. Initially, there are no tape drives currently in use. When the first application opens a tape drive for use, the device driver assigns the application to use HBA1. When a second application opens a tape drive for use, the device driver assigns the second application to use HBA2. A third application would be assigned to HBA1 and a fourth application would be assigned to HBA2. There would be two applications using HBA1 and two applications using HBA2. If the first application finishes and closes the device, there would now be one application using HBA1 and two applications using HBA2. When the next application opens a tape drive, it would be assigned to HBA1, so again there would be two applications using HBA1 and two applications using HBA2. Likewise, if the second application finishes and closes the device, HBA2 would have one application using it and the next application that opens a tape drive would be assigned to HBA2. The dynamic load balancing support is independent from the automatic failover support. Regardless of the path assigned initially for load balancing, if that path fails, the automatic failover support attempts recovery on the next available path. Supported Devices and Feature Codes Path failover is supported only for the devices listed in Table 3. Path failover includes Control Path Failover (CPF) for tape libraries and Data Path Failover (DPF) for tape drives. In order to use path failover support, some devices require feature codes as listed in Table 3. Table 3. Supported Devices and Feature Codes Supported Tape Library Feature Code (FC), if required TS1120 Standard, no FC required (DPF only) TS1130 Standard, no FC required (DPF only) 3592 Standard, no FC required (DPF only) TS3500 FC 1682 (CPF and DPF) TS3400 Standard, no FC required (CPF and DPF) TS3310 FC 1682 (CPF and DPF) TS3320 FC 1682 (CPF and DPF) TS7520 FC 1682 (CPF and DPF) TS7650 Standard, no FC required (DPF only) 16 IBM Tape Device Drivers Installation and User's Guide

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
  • 166
  • 167
  • 168
  • 169
  • 170
  • 171
  • 172
  • 173
  • 174
  • 175
  • 176
  • 177
  • 178
  • 179
  • 180
  • 181
  • 182
  • 183
  • 184
  • 185
  • 186
  • 187
  • 188
  • 189
  • 190
  • 191
  • 192
  • 193
  • 194
  • 195
  • 196
  • 197
  • 198
  • 199
  • 200
  • 201
  • 202
  • 203
  • 204
  • 205
  • 206
  • 207
  • 208
  • 209
  • 210
  • 211
  • 212
  • 213
  • 214
  • 215
  • 216
  • 217
  • 218
  • 219
  • 220
  • 221
  • 222
  • 223
  • 224
  • 225
  • 226
  • 227
  • 228
  • 229
  • 230
  • 231
  • 232
  • 233
  • 234
  • 235
  • 236
  • 237
  • 238
  • 239
  • 240
  • 241
  • 242
  • 243
  • 244
  • 245
  • 246
  • 247
  • 248
  • 249
  • 250
  • 251
  • 252
  • 253
  • 254
  • 255
  • 256
  • 257
  • 258
  • 259
  • 260
  • 261
  • 262
  • 263
  • 264
  • 265
  • 266
  • 267
  • 268
  • 269
  • 270
  • 271
  • 272
  • 273
  • 274
  • 275
  • 276
  • 277
  • 278
  • 279
  • 280
  • 281
  • 282
  • 283
  • 284
  • 285
  • 286
  • 287
  • 288
  • 289
  • 290
  • 291
  • 292
  • 293
  • 294
  • 295
  • 296
  • 297
  • 298
  • 299
  • 300
  • 301
  • 302
  • 303
  • 304
  • 305
  • 306
  • 307
  • 308
  • 309
  • 310
  • 311
  • 312
  • 313
  • 314
  • 315
  • 316
  • 317
  • 318
  • 319
  • 320
  • 321
  • 322
  • 323
  • 324
  • 325
  • 326
  • 327
  • 328
  • 329
  • 330
  • 331
  • 332
  • 333
  • 334
  • 335
  • 336
  • 337
  • 338
  • 339
  • 340
  • 341
  • 342
  • 343
  • 344
  • 345
  • 346
  • 347
  • 348
  • 349
  • 350
  • 351
  • 352
  • 353
  • 354
  • 355
  • 356
  • 357
  • 358
  • 359
  • 360
  • 361
  • 362
  • 363
  • 364
  • 365
  • 366
  • 367
  • 368
  • 369
  • 370
  • 371
  • 372
  • 373
  • 374
  • 375
  • 376
  • 377
  • 378
  • 379
  • 380
  • 381
  • 382
  • 383
  • 384
  • 385
  • 386
  • 387
  • 388
  • 389
  • 390
  • 391
  • 392
  • 393
  • 394
  • 395
  • 396
  • 397
  • 398
  • 399
  • 400
  • 401
  • 402
  • 403
  • 404
  • 405
  • 406
  • 407
  • 408
  • 409
  • 410
  • 411
  • 412
  • 413
  • 414
  • 415
  • 416
  • 417
  • 418
  • 419
  • 420
  • 421
  • 422
  • 423
  • 424
  • 425
  • 426
  • 427
  • 428
  • 429
  • 430
  • 431
  • 432
  • 433
  • 434
  • 435
  • 436
  • 437
  • 438
  • 439
  • 440
  • 441
  • 442
  • 443
  • 444
  • 445
  • 446
  • 447
  • 448
  • 449
  • 450
  • 451
  • 452
  • 453
  • 454
  • 455
  • 456
  • 457

Dynamic Load Balancing
The dynamic load balancing support optimizes resources for tape devices that have
physical connections to multiple Host Bus Adapters (HBA) in the same machine.
When an application opens a device that has multiple HBA paths configured, the
device driver determines which path has the HBA with the lowest usage, and
assigns that path to the application. When another application opens a different
device with multiple HBA paths, the device driver again determines the path with
the lowest HBA usage and assigns that path to the second application. The device
driver updates the usage on the HBA assigned to the application when the device
is closed. Dynamic load balancing uses all Host Bus Adapters whenever possible
and balance the load between them to optimize the resources in the machine.
For example, consider a machine with two Host Bus Adapters, HBA1 and HBA2,
with multiple tape drives attached. Each tape drive is connected to both HBA1 and
HBA2. Initially, there are no tape drives currently in use. When the first application
opens a tape drive for use, the device driver assigns the application to use HBA1.
When a second application opens a tape drive for use, the device driver assigns
the second application to use HBA2. A third application would be assigned to
HBA1 and a fourth application would be assigned to HBA2. There would be two
applications using HBA1 and two applications using HBA2.
If the first application finishes and closes the device, there would now be one
application using HBA1 and two applications using HBA2. When the next
application opens a tape drive, it would be assigned to HBA1, so again there
would be two applications using HBA1 and two applications using HBA2.
Likewise, if the second application finishes and closes the device, HBA2 would
have one application using it and the next application that opens a tape drive
would be assigned to HBA2.
The dynamic load balancing support is independent from the automatic failover
support. Regardless of the path assigned initially for load balancing, if that path
fails, the automatic failover support attempts recovery on the next available path.
Supported Devices and Feature Codes
Path failover is supported only for the devices listed in Table 3. Path failover
includes Control Path Failover (CPF) for tape libraries and Data Path Failover
(DPF) for tape drives. In order to use path failover support, some devices require
feature codes as listed in Table 3.
Table 3. Supported Devices and Feature Codes
Supported Tape Library
Feature Code (FC), if required
TS1120
Standard, no FC required (DPF only)
TS1130
Standard, no FC required (DPF only)
3592
Standard, no FC required (DPF only)
TS3500
FC 1682 (CPF and DPF)
TS3400
Standard, no FC required (CPF and DPF)
TS3310
FC 1682 (CPF and DPF)
TS3320
FC 1682 (CPF and DPF)
TS7520
FC 1682 (CPF and DPF)
TS7650
Standard, no FC required (DPF only)
Path Failover
16
IBM Tape Device Drivers Installation and User’s Guide