In this article I would like to discuss about the new and outstanding technology i.e “Storage VMotion”. Till now we heard about What is VMotion? How it Happens?. With that knowledge we are going forward to learn about this new feature in vSphere. Storage VMotion is similar to VMotion in means of migrating Virtual Machine from one location to another with out downtime or without disturbance in the services. When we initiate VMotion the reference of the Virtual Machine moves from one host to another host, but not the data which is related to that VM. With Storage VMotion reference of the Virtual Machine remains in the same location, but the data moves from one location (storage) to another location (storage).
Let’s check this out how it works….
VMware Storage VMotion allows virtual machine storage disks to be relocated to different datastore locations with no downtime, while being completely transparent to the virtual machine or the end user.
Before moving a virtual machines disk file, Storage VMotion moves the “home directory” of the virtual machine to the new location. The home directory contains meta data about the virtual machine (configuration, swap and log files). After relocating the home directory, Storage VMotion copies the contents of the entire virtual machine storage disk file to the destination storage host, leveraging “changed block tracking” to maintain data integrity during the migration process. Next, the software queries the changed block tracking module to determine what regions of the disk were written to during the first iteration, and then performs a second iteration of copy, where those regions that were changed during the first iteration copy (there can be several more iterations).
Once the process is complete, the virtual machine is quickly suspended and resumed so that it can begin using the virtual machine home directory and disk file on the destination datastore location. Before VMware ESX allows the virtual machine to start running again, the final changed regions of the source disk are copied over to the destination and the source home and disks are removed. This approach guarantees complete transactional integrity and is fast enough to be unnoticeable to the end user.
Storage VMotion facilitates us to do Storage Upgrades / Maintenance & supports to optimize the storage performance with out downtime. The best advantage of Storage VMotion is we can efficiently utilize our storage resources.
“Watch this video i have recorded with VMotion and Storage VMotion demonstrations”
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