On Sun Fire T1000/T2000 field could replace DIMMs individually, it is not required to replece
DIMMs by pair or bank.

For Sun Fire T1000

• 2 Ranks per channel (Rank0 – 2xDIMMs, Rank1 – 2xDIMMs).
• 4 DIMMs slot per channel – max total 8xDDR-2 DIMMs in 2 channels)
• All channels must be populated in the same way (Both Rank0 and Rank1, OR Rank0 ONLY – min of 4xDIMMs)
• All DIMMs must be identically sized

So Memory DIMMs must be installed four at a time (with one pair on each controller). All DIMMs must have identical capacity. Two basic memory configurations are supported: 4-DIMM or 8-DIMM

For Sun Fire T2000

• 2 Ranks per channel (Rank0 – 2xDIMMs, Rank1 – 2xDIMMs).
• 4 DIMMs slot per channel – max total 16xDDR-2 DIMMs in 4 channels)
• All channels must be populated in the same way (Both Rank0 and Rank1, OR Rank0 ONLY – min of 8xDIMMs)
• All DIMMs must be identically sized

So Memory DIMMs must be installed eight at a time (with one pair on each controller). All DIMMs must have identical capacity. Two basic memory configurations are supported: 8-DIMM or 16-DIMM

The Tx000′s DIMM modules are provided as pair when ordered with the option number, shown in the Sun System Handbook:

• X7800A Buy 1GB (2 ? 512MB DDR2) Memory Expansion Kit, RoHS:Y
• X7801A Buy 2GB (2 ? 1GB DDR2) Memory Expansion Kit, RoHS:Y
• X7802A Buy 4GB (2 ? 2GB DDR2) Memory Expansion Kit, RoHS:Y
• X7803A Buy 8GB (2 ? 4GB DDR2) Memory Expansion Kit

When a DIMM failure occurs, we can order single DIMM as CRU using the ‘spares ordering process’. And those CRU are also provided as one DIMM base in SSH:

• 370-6207 512MB DDR2 DIMM, 533 MHz, RoHS:Y
• 370-6208 1GB DDR2 DIMM, 533 MHz, RoHS:Y
• 370-6209 2GB DDR2 DIMM, 533 MHz, RoHS:Y
• 370-6210 4GB DDR2 DIMM, RoHS:Y

Tx000 also support mixing DIMMs from different vendors and it is not required to replace those DIMMs by pair.