General information which we should remember in xenserver are pointed here:

• Xenserver is paravirtualized hypervisor. Hence, it needs Intel-VT or AMD-V to be enabled.
• MTU, Short for Maximum Transmission Unit, the largest physical packet size, measured in bytes, that a network can transmit. Any messages larger than the MTU are divided into smaller packets before being sent.
• Open vSwitch combined with Distributed vSwitch Controller gives you more features.
• We want to delete the snapshots of an existing VM, but not the original VM, we right click on the VM and choose Delete VM. Then in the next screen, we can select the snapshots and click delete. Now the original VM’s details are also deleted from xencenter. We wont be able to see that VM in xencenter, but its original Hard disk files are present in our storage.If we want to restore it back, create new VM and point to the existing VM harddisk file.
• When we want to enable Graphics processing unit, we can do it in vm properties. when it is enabled, VNC will be disabled. So, we need to enable remote desktop to the vm and then enable GPU.Intel VT-d must be enabled on the CPU.
• When you are exporting any VM from xencenter, it is better to export it in ovf/ova format because vmware and hyperv also can understand ovf/ova format. Hence, if needed you can import the vm to vmware or hyperv.
• Multipathing: We have a storage and we can have two FC fabrics pointing to the same storage. From our xenserver we reach to fabric1 and then to our storage and from our XS to fabric2 and then to our storage. This is useful when fabric1 goes down, the second one(fabric2) comes to live automatically.
• when you create nfs storage, read/write permission must be given for root access. Now you can create nfs vhd storage in xenserver.
• Windows Virtual machines templates should be configured using microsoft SYSPREP utility.
• When ever we refer to SAN, it is a block level transfer.NAS data transfer model is file level and iscsi and fiber channel use Block level.
• shared storage is automatically made available to other hosts in pool, meaning, it will pull out the shared storage out of the one to which it is attached and it will make the storage available for all the hosts in the pool.
• what ever network is added to the vm, check in the networking tab, if it is activated or not.
• To check if a xenserver host is in open vswitch or linux bridge, use the command, cat /etc/xensource/network.conf. It would then show linux bridge or open vswitch as output.
• n/w and storage are controlled by dom0. ram and cpu are controlled by paravirtualization from xenserver h/w.
• if there is any prb with n/w or storage, you can restart xen tool stack.
• cluster is collection of servers(vms not hypervisors)resource pool is a collection of xenservers(hypervisors)
• vdi in xs is virtual disk image.
• In PVS,when a master image is booted from hard disk, its boot sector gets locked and it will not be available for capturing. So, we have to make the first boot device as network.
• Before installing pvs target device installation in your master image, if the first boot device is network, and if you start the machine, you might not find the vdisk created in pvs server. Change the boot preference to other than network and start the machine, configure target device installation and then change the boot oder to network as first preference and then reboot.
• Virtual Hard Disk (VHD) and Virtual Machine Disk (VMDK) format disk image files can be imported using the Import wizard.xenserver file format is xva.