6760 ServerNet/DA Manual

Introduction to the 6760 ServerNet/DA
6760 ServerNet/DA Manual—424879-003
1-11
6760 Adapters in Noninterleaved Enclosures
Balance 6760 Adapters Across Enclosures
When multiple 6760 adapters are installed in a processor enclosure and its attached
I/O enclosures, you should balance the adapters between even-numbered slots and
odd-numbered slots.
For example, if four 6760 adapters are installed in slot 54 of a processor enclosure and
its three attached I/O enclosures, all four adapters would be vulnerable to a Y-fabric
outage. This also means that if the PMF CRU in slot 55 of that processor enclosure
had to be removed, all devices connected to all four 6760 adapters would have to be
stopped.
Considerations for Disk Modules
Although it is possible to control both paths to the same disk module (in a 455mod8
module) using only one 6760 adapter, in order to be more fault tolerant, you should
install at least two 6760 adapters and enough SACs to properly populate each 6760
adapter for your system.
External disks attached to 6760 adapters in non-interleaved enclosures can be
installed in one or two disk modules. The one-module configuration is shown in
Figure 1-8 on page 1-12; the two-module configuration is shown in Figure 1-9 on
page 1-13.
Either the one-module configuration or the two-module configuration can tolerate the
failure of a ServerNet fabric. However, the two-module configuration is recommended
for mirrored disks, because fault tolerance is improved when the primary and mirror
disks of a mirrored volume are in separate disk modules.