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1. #Vm has more disk space than reported by netapp full#
2. #Vm has more disk space than reported by netapp windows#

Then the virtual disk will pull blocks of space from the storage capacity to match the needs of the written data amount.įigure 6. No storage capacity is consumed until you actually put data on these virtual disks. Even if you don’t have a storage array that provides you with thin provisioning, you can enjoy its benefits due to the dynamically expanding VHDX format.

#Vm has more disk space than reported by netapp windows#

With Windows Server 2012, Microsoft introduced the VHDX file format, which brings better performance, resilience and data protection. Windows reporting 2.59 TB in use while in reality only 402 GB is consumed on the SAN. So, they only consume the needed space on the thin provisioned LUN within the SAN, but Windows doesn’t know any better and reports the actual fixed VHDX file sizes.įigure 5. There’s a nice collection of fixed VHDX files on this CSV that are filled with just an OS and nothing more. The OS size reported by CSV vs the actual space consumed on the SAN. As an extreme example, take a look at the same LUN as above.įigure 4.

#Vm has more disk space than reported by netapp full#

So, the OS reports way higher storage use on a CSV LUN full of VMs with fixed VHDX size or dynamically expanding VHDX files than the SAN. The same applies for dynamically expanding VHDX files – on which space has been recovered on the SAN, but where the file hasn’t shrunk yet. The OS is not aware that a fixed VHDX is only really consuming 10 GB out of 50 GB or 127 GB, but the SAN knows. Notice that your SAN is often more efficient at identifying storage space that is actually used than the operating system. The space reclaimed after UNMAP operation. We’ll delete about 200GB of files and see that amount of space reclaimed on the SAN.įigure 3. A 10.5 TB LUN with 402.01 GB of actual storage consumed on the SAN This shows that the actual space we are using on the SAN is 402 GB, the rest of that 10.5 TB is not allocated.įigure 2. Now let’s take a look at this 10.5 TB LUN on a SAN where we first disabled snapshots storage level. Not all storage devices support thin provisioning, so make sure to check with your specific vendor to validate its supported devices. Likewise, when you create a 50 TB LUN on a SAN that only has 30 TB in total capacity, you’ll be in trouble when you actually try to copy that much data on to the LUN. Once your virtual hard disk outgrows the space available, your LUN won’t have any operating room left and your VMs will suffer down time. New Virtual Hard Disk Wizard in Hyper-V Manager What happens under the hood with thin provisioning is that you’re making the operating system think it has capacity, but in actuality it doesn’t know that the storage is completely exhausted.įigure 1. First, you might consume the maximum space allocated in the dynamically expanding VHDX or even consume all of the capacity on your storage array at some point. As previously mentioned, this presents challenges. The fixed disk type physically writes out zeroes to the 200GB so the space is immediately consumed. The dynamic disk allows you to specify 200GB worth of capacity to the Guest VM and operating system, but in actuality it’s dynamically expanding out as data within the application is written.

When adding the disk, you have the option of creating either a fixed disk or a dynamic disk. Within Hyper-V we create the operating system and then attach our second data disk, VHDX. We have an application that physically requires 200GB worth of capacity. Let’s take a look at a real-life example. The benefits of this provisioning are clear, however, there are some downsides to it as well. This mechanism uses storage space more efficiently and helps prevent against the wasting of resources on reservations that could never be used. Thin provisioning is the process of making a host think it has more available storage capacity than it actually has by allocating the needed disk space on demand.