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Frequently Asked Questions for UCS



Q: What is Cisco Unified Computing System?

Ans: Cisco Unified Computing System (UCS) unites physical and virtual computational and network resources into a single system. UCS is a set of pre-integrated data center components that comprises blade servers, adapters, fabric interconnects, and extenders that are integrated under a common embedded management system. This approach results in far fewer system components than comparable data center platforms.

Q: Which operating systems (OS) are supported on UCS?

Ans: UCS blade servers are certified for following OS:

  1. Microsoft Windows Server 2008
  2. Microsoft Windows Server 2003 R2
  3. Red Hat Enterprise Linux 5.3
  4. Red Hat Enterprise Linux 4.8
  5. Novell SUSE Linux Enterprise Server 11
  6. VMware vSphere 4
  7. VMware Infrastructure 3.5 Update 4


Q: Which hypervisors are supported on UCS?

Ans: Cisco UCS supports several hypervisors including VMware ESX, ESXi, Microsoft Hyper-V, Citrix XenServer and others. Guest operating systems are limited to 255 GB of vRAM and 8 virtual processors in vSphere 4.x, upgraded to 1 TB of vRAM and 32 vCPUs in vSphere 5.0. Additionally, the Cisco UCS Virtual Interface Cards incorporate VM-FEX technology that gives virtual machines direct access to the hardware for improved performance and network visibility.

Q: From where to download OS patches and drivers?

Ans: You should download OS patches from the respective vendors. Drivers that are not part of OS and supplied by Cisco can be downloaded from

Q: Does UCS support netflow?

Ans: No, UCS does not support netflow.

Q: Can I use a Nexus 5000 as a UCS 6100 fabric interconnect?

Ans: No, Nexus 5000 is a general purpose L2 switch and UCS 6100 series is an integral part of the unified computing system. The software that runs on the UCS 6100 is different from the Nexus 5000, as the UCS 6100 has both control and management planes.


Q: What are UCS Blade Servers and Rack Servers?

Ans: UCS Blade Servers sit inside the UCS chassis and are managed using UCS manager. UCS Rack Servers work independently and do not require the full UCS infrastructure; however they can also be integrated in your existing UCS infrastructure. For a full list of differences between UCS Blade Servers and Rack Servers click here.


Q: What is UCS Express?

Ans: UCS express is compact, all-in-one computing and networking system targeted at branch offices. UCS express is build on the concept of lean branch office which reduces the branch-office infrastructure footprint, equipment and operating costs, and management complexity. Main components of UCS express are ISR Generation2 series router and Services Ready Engine (SRE) multipurpose x86 blade servers. Cisco ISR G2 functions as a blade-server enclosure for SRE blade servers, which in themselves run branch office applications like DNS, DHCP, etc. The system comes with VMware vSphere Hypervisor for virtualization and CIMC Express for blade server management. For more information click here.


Q: What are UCS E-series servers?

Ans: UCS E-Series Server modules are next-generation, power-optimized, x86, Intel® Xeon® 64-bit blade servers designed to be deployed in Cisco Integrated Services Routers Generation 2 (ISR G2). The Cisco UCS E-Series Servers extend the Cisco UCS product portfolio to meet the needs of customers who want to deploy a virtualization-ready computing infrastructure in the branch-office environment while maintaining a lean branch-office architecture. E-series servers are a good replacement for UCS express SRE. For more info on E-series servers click here.

Q: How are the ports mapped from server to fabric interconnect in UCS?

Ans: Port mapping from server to fabric interconnect is automatic in UCS. If the number of links from fabric extender to fabric interconnect is only one then all of the 8 ports are pinned to it. If the number of links from fabric extender to fabric interconnect is two then ports 1,3,5,7 are pinned to first link and ports 2,4,6,8 are pinned to second link. If the number of links from fabric extender to fabric interconnect is four then ports 1,5 are pinned to first link; port 2,6 are pinned to second link; port 3,7 are pinned to third link; and port 4,8 are pinned to fourth link. Remember that three link topology is not supported in UCS.

Q: What is the maximum number of VLANs supported in UCS?

Ans: As of version 1.3(1), UCS supports up to 512 VLANs. Remember that VLANs 3968 to 4048 are reserved and can not be used.

Q: If I have forgotten UCS password, how to recover it?

Ans: If you have forgotten the password, you can set a new password. Connect to the console of UCS 6100 series fabric interconnect. Reload the fabric interconnect and when it boots up hit ctrl+L or ctrl+shift+R to go to loader prompt then boot the kickstart image; if you have two fabric interconnects connected in HA then first reload the subordinate fabric interconnect and bring it in loader prompt and then reload the primary and bring it in loader prompt, after this load kickstart image on primary. Configure the admin password using "admin-password" command by going to config terminal mode. Now load the system image on the fabric interconnect or if you have HA load system image on the primary fabric interconnect. The password is now set to the new password you have just configured; if you have HA then now you can load the kickstart and system images on the subordinate fabric interconnect.

Q: What is the maximum number of user sessions supported on UCS?

Ans: The maximum number of users that can be created on UCS is 48, this includes any kind of user. The maximum number of GUI sessions (accessing UCS manager via http) supported is 256. The maximum number of CLI sessions (telnet and SSH combined) supported is 32. Remember that CLI and GUI sessions are treated as separate; hence you can have at the max 256 GUI sessions and 32 CLI sessions at the same time.

Q: If the fabric extender is connected to fabric interconnect using 4 links and one of the links fail, what will happen?

Ans: The server interfaces that are affected will either lose connectivity or fail over to another fabric extender, depending if interface is created as a HA interface. UCS M71KR-E/ UCS M71KR-Q Converged network adapter has the capability to fail over Ethernet interfaces if so configured. UCS 82598KR-CI 10 Gigabit Ethernet Adapter does not have this capability. Fibre Channel interfaces that are pinned to failing fabric extender link will just fail and their HA capability depends purely on host side multipathing driver. If HA/mutipathing is not configured for Ethernet/Fibre Channel then servers connected to the failed link will loose connectivity but the other three links will be working as usual. Remember that no automatic re-pinning will happen. You can manually re-pin the servers using two link topology, since three link topology is not supported.