Expanding Private Cloud Appliance Capacity with a Compute Expansion Rack
To increase the compute capacity beyond the physical limits of the base rack, Private Cloud Appliance can be expanded with compute nodes installed in a compute expansion rack.
A compute expansion rack contains 3, 6, 9, or 12 factory-installed nodes. More nodes can be installed after initial deployment, but always in sets of 3. Up to two expansion racks can be connected to a base rack, for a maximum of 24 compute nodes in addition to those already installed in the base rack. For more information, see Compute Expansion Rack Configuration.
Installation Requirements
- Site Preparation
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If you have decided to expand your Private Cloud Appliance environment with a compute expansion rack, carefully plan ahead for the installation of the additional hardware. The expansion rack has the same external dimensions as the base rack, and contains the same type of hardware. Therefore, the base rack site requirements also apply for the expansion rack. They are described in detail in Preparing the Installation Site.
- Rack Cabling
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The cable connections between the base rack and the compute expansion rack must not exceed 25 meters. Allocate a space for the expansion rack near the base rack, ensuring that the inter-rack cabling is within the specified maximum length when routed through the floor or ceiling. The required cable length must be specified with the order. The default length of cables included in the shipment is 10 meters.
Connecting the Expansion Rack to the Base Rack
When the compute expansion rack is in its allocated space, it must be connected to the base rack. The expansion rack leaf switches are cross-connected to the base rack spine switches to extend the data network into the expansion rack. Similarly, the expansion rack components are added to the internal management network through a cable connection between the management switches in the racks. The ports required for this setup have been reserved on all connected switches.
- Connecting the Management Switches
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A compute expansion rack management switch must be connected to the base rack management switch using two cable links with 25Gbps SFP28 transceivers.
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On the side of the compute expansion rack, use management switch ports 49 and 50.
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Connect the cables from the first compute expansion rack to base rack management switch ports 49 and 50. Connect the cables from the second compute expansion rack to base rack management switch ports 51 and 52.
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- Connecting the Leaf Switches
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Each compute expansion rack leaf switch has redundant cross-connections to the two spine switches of the base rack. There are 8 total cable links between a GPU expansion rack and the base rack, using 100Gbps QSFP28 transceivers.
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On the side of the compute expansion rack, use ports 33-36 in each leaf switch.
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Connect the cables from the first compute expansion rack to the base rack spine switches using this pattern:
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Leaf1 (RU18/pcaswlf03) ports 33 and 34 to Spine1 (RU29/pcaswsp01) ports 11 and 12
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Leaf1 (RU18/pcaswlf03) ports 35 and 36 to Spine2 (RU30/pcaswsp02) ports 11 and 12
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Leaf2 (RU19/pcaswlf04) ports 33 and 34 to Spine1 (RU29/pcaswsp01) ports 13 and 14
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Leaf2 (RU19/pcaswlf04) ports 35 and 36 to Spine2 (RU30/pcaswsp02) ports 13 and 14
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Connect the cables from the second compute expansion rack to the base rack spine switches using this pattern:
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Leaf1 (RU18/pcaswlf05) ports 33 and 34 to Spine1 (RU29/pcaswsp01) ports 15 and 16
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Leaf1 (RU18/pcaswlf05) ports 35 and 36 to Spine2 (RU30/pcaswsp02) ports 15 and 16
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Leaf2 (RU19/pcaswlf06) ports 33 and 34 to Spine1 (RU29/pcaswsp01) ports 17 and 18
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Leaf2 (RU19/pcaswlf06) ports 35 and 36 to Spine2 (RU30/pcaswsp02) ports 17 and 18
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When the physical connections are in place, the compute expansion rack must be activated. For more information, see Integrating a Compute Expansion Rack.