Disk Load Balancing, Fault Tolerance, and Configuration Limits for NonStop Systems

Example 1

Volume CPUs –P SAC –B SAC –M SAC –MB SAC

$D1 0,1 (110,2,1) 1 (110,3,1) 1 (110,3,2) 1 (110,2,2) 1

$D2 1,0 (110,2,1) 1 (110,3,1) 1 (110,3,2) 1 (110,2,2) 1

$D3 2,3 (110,2,1) 1 (110,3,1) 1 (110,3,2) 1 (110,2,2) 1

$D4 3,2 (110,2,1) 1 (110,3,1) 1 (110,3,2) 1 (110,2,2) 1

$D5 0,1 (110,2,1) 2 (110,3,1) 2 (110,3,2) 2 (110,2,2) 2

$D6 1,0 (110,2,1) 2 (110,3,1) 2 (110,3,2) 2 (110,2,2) 2

$D7 2,3 (110,2,1) 2 (110,3,1) 2 (110,3,2) 2 (110,2,2) 2

$D8 3,2 (110,2,1) 2 (110,3,1) 2 (110,3,2) 2 (110,2,2) 2

$D9 0,1 (110,3,1) 1 (110,2,1) 1 (110,2,2) 1 (110,3,2) 1

$D10 1,0 (110,3,1) 1 (110,2,1) 1 (110,2,2) 1 (110,3,2) 1

$D11 2,3 (110,3,1) 1 (110,2,1) 1 (110,2,2) 1 (110,3,2) 1

$D12 3,2 (110,3,1) 1 (110,2,1) 1 (110,2,2) 1 (110,3,2) 1

$D13 0,1 (110,3,1) 2 (110,2,1) 2 (110,2,2) 2 (110,3,2) 2

$D14 1,0 (110,3,1) 2 (110,2,1) 2 (110,2,2) 2 (110,3,2) 2

$D15 2,3 (110,3,1) 2 (110,2,1) 2 (110,2,2) 2 (110,3,2) 2

$D16 3,2 (110,3,1) 2 (110,2,1) 2 (110,2,2) 2 (110,3,2) 2

The second example shows 8 mirrored CLIM-attached disk volumes load balanced in every way.

• Across 4 processors

– 2 IOPs primary in each processor

– 2 IOPs backup in each processor

• Across 4 CLIMs

– 8 configured paths through each CLIM

– 4 active paths through each CLIM

• Across each combination of processor and CLIM

– 4 configured paths from each processor to each CLIM

– 2 active paths from each processor to each CLIM

– 1 active path from each primary processor to each CLIM

Example 2

Volume CPUs –P –B –M –MB

$D21 0,1 C100251 C100261 C100263 C100253

$D22 1,0 C100251 C100261 C100263 C100253

$D23 2,3 C100251 C100261 C100263 C100253

$D24 3,2 C100251 C100261 C100263 C100253

$D25 0,1 C100261 C100251 C100253 C100263

$D26 1,0 C100261 C100251 C100253 C100263

$D27 2,3 C100261 C100251 C100253 C100263

$D28 3,2 C100261 C100251 C100253 C100263