VMware Storage : A Place to store VM’s
Its been long time from m previous post, almost 1 week. Sorry guys. In this post i want to discuss about the types of storage used in VMware Infrastructure.
Storage: Its a place for the computers where all the information is stored. In general we use Hard disks, USB Sticks and CD/DVD’s as our regular storage. But with these devices we can store a limited data only. And as data is the most important thing in the world for every techie guyd and every organization, there are lot of technologies introduced to provide security to the data in the form of Backup, Availability and Scalability.
Backup, Data Availability or Scalability, what ever the concept is, it’s main target is to provide a copy of original data in the time of Loss of data. May be all of you guys are aware of all these concepts. If you want me to explain these also, please mail me at email@example.com
In our computers we will install HDD’s to store operating system file and applications. In the same way VMware ESX server uses local storage to store the operating system files. When we create one or two Virtual Machines on this ESX server they will get the space for the .vmdk files from the same local storage. So the local storage has a limitation of providing the space to all Virtual Machines (more than 2). In this case we need to provide extra storage for all the virtual machines that are residing on this ESX Server. This can be achieved using latest storage technologies FC SAN, iSCSI SAN & NFS. Apart from these we can assign LUN’x directly to the virtual machines RDM (Raw Device Mappings).
FC SAN (Fiber Channel Storage Area Network) : It is the most efficient way to provide storage to the Virtual Environment. If you want to read more about SAN, please click here. In this technology (FC SAN), HBA cards and Optical Fiber Cables are used to Access the storage. The storage is access in the form of Blocks. And as we are using Optical Fiber cables for communication the data transfer speed is very high. VMware has limited support to the HBA cards, only some specific models are supported by VMware. The storage is allocated in the form of LUNS( A specific size of space taken from different number of hard disks) , and these LUN’s will have a unique address which is called as WWN (World wide number) and the same used to access the LUN from the ESX Server/VM.
iSCSI SAN : It is another way of accessing the storage. In this technology the same LUN’s created and allocated for ESX server and VM’s. But the way communication is done using the Ethernet cards and RJ45 Cables. Here the identification of storage is IPaddress. It is very easy to configure and as most of the Ethernet cards are supported by VMware there is a good scope in using iSCSI SAN. And the data transfer speed is reasonable so as the Cost to implement is also very less when compared to FC SAN.
NFS ( Network File System) : This is a future of UNIX Operating Systems. You can create a NFS share in a UNIX server and the same can be made available to the ESX Server to store the virtual machines. This communication is done the same way of our regular network communication. You just need to provide the NFS share path to the ESX server in storage options, so that it will be mounted and comes available to ESX Server.
RDM (Raw Device Mappings) : Generally when we create a Virtual Machine we will create/allocate some space to the .vmdk file which is used as the internal hard disk for the Virtual Machine. We can create/allocate space for .vmdk file from the above 3 storage types. But those cannot be directly accessed by the Virtual Machine. First ESX server accesses it and it passes that access to the Virtual Machine. But using RDM we can give direct access to the Virtual Machine to the above said storages. But one disadvantage of RDM is we cannot take snapshots if we configure it as Physical.
Remember whatever the storage we are using in the background, the file system used by VMware is VMFS. It is a cluster supported file system. Some of the enterprise futures of VMware are dependents on VMFS.
I will explain all these 4 concepts using real time scenarios in my coming posts. Please keep visiting my blog.
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