Yes you can and but if it does not detect then you can reboot once SP at a time. Please make sure the SAS cables are connected correctly. I have also attached a document that would help you to identify the issue. The following is a Primus(R) eServer solution:  ID: emc265195Domain: EMC1Solution Class: 3.X Compatibility  Symptom    Storage system does not detect inserted drive  Symptom    Environmental data reporting may not reflect current environment  Symptom    Health Check fails with Error Code: flr::check_for_no_pulled_disks_3  Symptom    Health Check fails with Error Code: flr::check_for_transitions_2  Symptom    Health Check fails with Error Code: platform::check_for_enclosure_faults_2  Symptom    Health Check fails with Error Code: flr::check_for_trespassed_luns_1  Symptom    Health Check fails with Error Code: flr::check_for_unowned_luns_1  Symptom    Storage system blower speed is set to High  Symptom    Storage system does not detect insertion of power supply, LCC, or insertion of SP  Symptom     The following tables describes which symptoms appear for which DAEs and DPEs.   VNXe 3300 VNXe 3100 Symptom DPE DAE DPE DAE Does not detect inserted drive Y   Y Y Incorrect environmental data reporting       Y Blower speed is set to High       Y Does not detect insertion of Power Supply       Y Does not detect peer LCC or insertion of SP  Y   Y Y   Cause      Common Disk Enclosure Software (CDES) is the firmware used for the SAS Expander in a VNXe Disk Processor Enclosure (DPE) and a Disk Array Enclosure (DAE).  A timer overflow occurs in version 1.13 of CDES 42 days after the SAS expander is rebooted.  When the timer rolls over, the listed behaviors can occur.  Fix        Update to VNXe Operating Environment (SP2 · 2.0.2.12987) or later. This version contains CDES version 1.16. If the VNXe has been running for 42 days or more with an older version, power-cycle it before the update. Check what version of system software is running on the VNXe.   Power-cycle the system if it has been running for 42 days or more. See Knowledgebase article emc263167 for power-cycle procedure.     Update the system software on the VNXe.   Note       If your system has been running for over 42 days, and you run the Health Check prior to power-cycling the system (clicking on Health Check button), the Health Check results may not be valid. You may receive one or more of the following errors. Ignore the errors. Power-cycle the system as shown in the Fix section. Rerun the Health Check after the power-cycle to verify that it now succeeds.  The health check has failed. There are disks or software components which are currently removed or faulted. Please visit the Health page to check for failed or missing disks, attempt to resolve any disk issues found, and then retry the health check. If this does not solve the problem, record the error code below and search the EMC Online Support website for available support options. [Error Code: flr::check_for_no_pulled_disks_3]    The health check has failed. A problem has been detected with a backend DAE, please check that the backend cabling is correct and then visit the Health page to identify and attempt to resolve any hardware issues. Correct any issues found and re-run the health check. If this does not solve the problem, record the error code below and search the EMC Online Support website for available support options. [Error Code: platform::check_for_enclosure_faults_2]    The health check has failed. An internal error is preventing the health check from completing successfully. Please reboot all Storage Processors (SPs) one at a time and then retry the health check. If this does not solve the problem, record the error code below and search the EMC Online Support website for available support options. [Error Code: flr::check_for_trespassed_luns_1]    The health check has failed. The ownership of some LUNs is incorrect. Please manually failback any Shared Folder/iSCSI servers and retry health check. If problem persists, reboot each of the Storage Processors and re-run the health check. If this does not solve the problem, record the error codes and search the EMC Online Support website for available support options. [Error Code: flr::check_for_unowned_luns_1]    The health check has failed. There are disks or software components which are currently recovering from a fault. Please visit the Health page to check for failed or missing disks, attempt to resolve any disk issues found, and then retry the health check. If this does not solve the problem, record the error code below and search the EMC Online Support website for available support options. [Error Code: flr::check_for_transitions_2]   In rare instances, the Health Check can continue to fail with similar errors after the power-cycle. These errors are valid and should be cleared prior to the system software update. If you receive the flr::check_for_transitions_2 error (the last error listed above) and you recently inserted a disk, the error is valid. Go to the Health page and wait until the disk has recovered. Then retry the update.  Note       See EMC Knowledgebase article emc265311 for information on CDES 1.13 and VNX series systems.
Can I add a new DAE self to the VNXe 3100 while the system is up and running?  I have read the documentation on adding the DAE and it does not mention shutting anything down first but then again it does not say you can add it while the system is running.
Adding a DAE