Upgrade limitations Check that you are aware of upgrade limitations before commencing the upgrade process. Multiple SDSs on the same server The installation of multiple SDS instances on the same server is no longer supported. To guarantee a better customer experience and improved stability, PowerFlex currently only supports a single SDS per server. As previous releases of PowerFlex supported the installation of multiple SDS instances per server (up to four), existing nodes using the multiple-SDS feature should be reconfigured in order to be eligible for an upgrade. Please consult with your Dell EMC Professional Services contact to assist with this configuration change, before you upgrade your system. NVDIMM capacity requirements for future upgrades Increased NVDIMM capacity per SDS is mandatory in PowerFlex version 3.5 or higher that contain Fine Granularity Storage Pools. If your system has insufficient NVDIMM capacity for PowerFlex v3.5 or higher, you will not be able to upgrade your system, and a warning alert will be generated. An upgrade readiness tool is provided with this release of PowerFlex to help you check your system. Instructions for doing so are described in the "Post-Upgrade" section of this guide, and in the Configure and Customize PowerFlex Guide. If the tool recommends more NVDIMM capacity, contact your account manager for assistance before you upgrade your system. NVDIMM 4k alignment On nodes configured with NVDIMMs, ndctl and daxio packages must installed before performing the upgrade: ndctl package—for example: ndctl-64.1-2.el7.x86_64.rpm daxio package—for example: daxio-1.5.1-2.1.el7.x86_64.rpm Parent topic IntroductionThis guide provides the upgrade procedures for PowerFlex components. PowerFlex v3.5 must NOT be deployed on hyperconverged (HCI) configurations at this time. Please ask your account team to submit an RPQ using the following link to request PowerFlex v3.5 support for HCI.