################################################################################ Oracle ASM disks - initialize "reclaimed" disk. If you cannot create the disk, after doing a delete, then try: Substitue XX for the device LETTER(S): dd if=/dev/zero of=/dev/sdXX1 bs=1024 count=100 ################################################################################ Definitions #=============================================================================== ESX/VM(ware) VMware ESX is VMware’s enterprise server virtualization platform. The platform is available in two versions -- ESX Server and ESXi Server. VMware ESX and ESXi can be deployed as part of the VMware infrastructure (vSphere or VMware View) to enable centralized management for data center applications and enterprise desktops. One main feature of the enterprise server virtualization platform is that it allows users to contain server sprawl by running software applications in virtual machines on fewer physical servers. #=============================================================================== vSphere vSphere is VMware's brand for its ESX and ESXi products. ESX is the company's flagship server virtualization product, which includes tools for datacenter management. For example, VMware's Vmotion enables virtual machines to be migrated live from one server to another. #=============================================================================== How Do VMware ESX and VMware ESXi Work? VMware ESX and VMware ESXi install directly on the server hardware, inserting a robust virtualization layer between the hardware and the operating system. VMware ESX and ESXi partition a physical server into multiple secure and portable virtual machines that can run side by side on the same physical server. Each virtual machine represents a complete system—with processors, memory, networking, storage and BIOS—so that an operating system and software applications can be installed and run in the virtual machine without any modification. Virtual machines are also completely isolated from each other by the virtualization layer, thus preventing a crash or configuration error in one virtual machine from affecting the others. Sharing the physical server resources among a number of virtual machines increases hardware utilization and dramatically decreases capital costs. The bare-metal architecture gives VMware ESX and ESXi complete control over the server resources allocated to each virtual machine and provides for near-native virtual machine performance and enterprise-class scalability. VMware ESX and ESXi provide virtual machines with built-in high availability, resource management and security features to deliver improved service levels to software applications than static physical environments. #=============================================================================== What is the difference between VMware ESX and VMware ESXi? VMware ESX and VMware ESXi are both bare-metal hypervisors that install directly on the server hardware. Both provide industry-leading performance and scalability; the difference resides in the architecture and the operational management of VMware ESXi. VMware ESX relies on a Linux operating system, called the service console, to perform some management functions including executing scripts and installing third-party agents for hardware monitoring, backup or systems management. The service console has been removed from VMware ESXi, dramatically reducing its footprint. By removing the service console, VMware ESXi completes an ongoing trend of migrating management functionality from this local command line interface to remote management tools. The functionally of the service console is replaced by remote command-line interfaces and adherence to system management standards. #=============================================================================== UCS Cisco's Unified Computing System (UCS) for their blade chassis management. A unified computing system (UCS) is a data center architecture that integrates computing, networking and storage resources to increase efficiency and enable centralized management. #=============================================================================== IP and/or DNS Name Virtualization There are a number of ways to virtualize IPs and “hostnames” (hostname being used here as meaning an “A-Records in DNS”, which hostnames do not have to be a part of DNS, but normally are so). Pro/Con of the two solutions Type DNS Alias/CNAME PRO Is not tied to any subnet (doesn’t use an IP) so is flexible between subnets/datacenters CON Must have a DNS change for it to take effect and/or moved and/or deleted. Also, if you don’t know what the CNAME is, you cannot search for it (hidden) unless you can look at the DNS zone files (currently locked down for outside query by DNS for security reasons). Must wait for DNS update (or do cache flush) for the changes to be in effect across the domain. VIP/IP alias (host side) PRO Easily seen on server. Easy to up/down the IP. Used by cluster technology (common use). Can easily find by getting on particular environment/server. CON Must be the same subnet as the NIC it will be plumbed up on (tied to subnet as well). Sometimes issues with resolution (delays) when switched to another MAC (ARP must be updated). Host Side VIPs IP Aliases on a host Virtual interface Additional IP for an interface (VIP/alias) More than one IP per NIC (VIPS or Aliases) (Clusters put service names on this way) eth0: inet 10.10.10.10 netmask 0xffffff00 broadcast 10.10.10.255 inet 10.10.10.11 netmask 0xffffff00 broadcast 10.10.10.255 inet 10.10.10.12 netmask 0xffffff00 broadcast 10.10.10.255 More then one Virtual NIC per NIC, each having its own IP Notice that it is INTERFACE:INSTANCE bond0 inet addr:10.10.10.x Bcast:10.10.10.127 Mask:255.255.255.192 bond0:1 inet addr:10.10.10.x Bcast:10.10.10.127 Mask:255.255.255.192 bond0:2 inet addr:10.10.10.x Bcast:10.10.10.127 Mask:255.255.255.192 bond0:3 inet addr:10.10.10.x Bcast:10.10.10.127 Mask:255.255.255.192 NOT virtual, but here for example. More than one NIC, but each NIC is for a separate subnet eth0: inet 192.168.x.x netmask 0xffffff00 broadcast 192.168.100.255 eth1: inet 192.168.x.x netmask 0xffffff00 broadcast 192.168.101.255 DNS: CNAME/alias CNAME (DNS Alias) for a server. A-Record is “myhost” and the CNAME/Alias is “nim”. nslookup myhost Name: myhost.mydomain.com Address: 10.10.10.2 nslookup nim base.mydomain.com canonical name = myhost.mydomain.com. Name: myhost.mydomain.com Address: 10.10.10.2 EXCEPTION for Oracle RAC Overloaded DNS entry - 3 IPs assigned to one name (DNS round-robin), done for Oracle RAC Scan IPs. Otherwise, not normally done (bad form). nslookup NAME Name: myserver.mydomain.com Address: 10.10.x.1 Name: myserver.mydomain.com Address: 10.10.x.2 Name: myserver.mydomain.com Address: 10.10.x.3 #------------------------------------------------------------------------------- VIPS and CNAMES/Aliases on F5/BigIP load balancers The F5/BigIP load balancers appliances can be configured with VIPs and have CNAMES (DNS aliases) pointing to those VIPS. Example Weblogic config on F5's (BigIP) 10.10.10.1 myserver.mydomain.com Notes: BigIP can be configured as: -local load balancers, -global load balancers, -link load balancers, -capacity balancing; using either: -round-robin, -weighted round-robin/preferred path, -least connections, -least response time; They can also keep "persistent connections" for users if configured. ################################################################################