When using Thick or Thin provisioning, ensure you test performance using Jetstress and LoadGen with the same provisioning type. Ensure alerting is configured and working to monitor capacity utilization especially when using thin provisioned VMDKs.
In a vSphere environment, What is the most suitable disk provisioning type to use for the LUN and the virtual machines to ensure minimum storage overhead and optimal performance? Ensure optimal storage capacity utilization 2. VAAI is supported and enabled 3. Increase flexibility 2. Ensure physical disk space is not unnecessarily wasted.
Optional Do not present more LUNs capacity than you have underlying physical storage Only over-commitment happens at the vSphere layer. Thin Provisioning minimizes the impact of situations where customers demand a lot of disk space up front when they only end up using a small portion of the available disk space 3.
Increases flexibility as all unused capacity of all datastores and the underlying physical storage remains available 4. Thin provisioning leaves maximum available free space on the physical spindles which should improve performance of the storage as a whole Where there is a real or perceved issue with performance, any VM can be converted to Thick Provisioned using Storage vMotion not disruptivley.
Using Thin Provisioned LUNs with no actual over-commitment at the storage layer reduces any risk of out of space conditions while maintaining the flexibility and efficiency with significantly reduce risk and dependency on monitoring. If the storage at the vSphere and array level is not properly monitored, out of space conditions may occur which will lead to downtime of VMs requiring disk space although VMs not requiring additional disk space can continue to operate even where there is no available space on the datastore 2.
The storage may need to be monitored in multiple locations increasing BAU effort 3. It is possible for the vSphere layer to report sufficient free space when the underlying physical capacity is close to or entirely used 4. When migrating VMs from one thin provisioned datastore to another ie: Storage vMotion , the storage vMotion will utilize additional space on the destination datastore and underlying storage while leaving the source thin provisioned datastore inflated even after successful completion of the storage vMotion.
Array level data replication is being used throughout the environment 4. Monitoring of the environment including vSphere and Storage is a manual process 5. The time frame to order new hardware eg: New Disk Shelves is a minimum of 3 months.
Simplified capacity management as only one layer vSphere layer needs to be monitored for capacity 2. To be able to reduce the VMDK file size of your thin-provisioned virtual disks, you need to know how to zero the blocks that the data you deleted previously occupied. NOTE : Disk shrinking operations are only possible if the virtual machines do not contain snapshots.
Also, please be attentive and execute commands at your own responsibility. Always back up all of your important data before carrying out any disk operations. We can try to delete unnecessary files on this virtual disk. However, Linux does not automatically zero blocks after deleting files; you will have to do this yourself.
You can do this by using the dd data duplicator utility for copying and converting data. This tool is available on all Linux systems. NOTE : Before running the dd utility, it is necessary to make sure the datastore has enough capacity to use it e. In our case, 10, MB is the amount of free space that we want to fill with zeroes, so the number of 1-Megabyte blocks is This is where you should indicate the source from which you want to copy data.
After executing the above command, the size of our VMDK file grows. This is the output we see after the successfully completed command:. This means that almost the whole root partition i.
This is because we have filled most of the previously "available" space with zeroes. Now, our thin-provisioned virtual disk is ready to be shrunk. Like Linux, Windows does not automatically zero blocks after deleting files. These commands will zero out any free space on your thin-provisioned disk by filling in any unused space on the specified partitions. Wait a couple of minutes until the process is finished. Your VMDK file will expand to its maximum size during the process.
For example, Microsoft clusters and Oracle programs often require this in order to qualify for support. When provisioning a thick eager zeroed disk, VMware pre-allocates the space and then zeroes it all out ahead of time. In other words, this takes a while — just to increase the net-new write performance of your virtual disk. In Hyper-V, by the way, this is called a fixed size disk. The below diagram shows the difference of these very clearly.
If you create the same size VMDK using the three different types, it will look roughly like this on the datastore:. A Raw Device Mapping is when an entire volume from the storage array is given directly to a single VM and the VM has full control over its volume.
You would want to leverage this for clustering, SAN-based snapshots, SAN-based replication or the ability to migrate a disk from a physical server to virtual or vice versa. There are two types of RDM: physical and virtual.
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