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Maximum volume size for VM for File server

  • 5 March 2021
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Hello, We have the VM with the file serber on installing on one of the node of our Nutanix. For now the size of the disk is 3.5 TB, but we wanted to extend this size up to 4.5TB. Is somebody knows if VM will work correctly with the such big size of the disk?

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Best answer by Sergei Ivanov 4 April 2021, 11:04

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Hi SergeySephora,

If the hypervisor is AHV, the virtual disk size is almost limitless. The theoretical maximum would be 9 exabytes. So, if the guest operating system supports the desired size, it is good to go.

However, i would recommend not to create large disks for performance reasons. In Nutanix we have write cache, which is called oplog and the oplog is always 6Gb in size. It is assigned per vdisk and it means that every vdisk has 6Gb of oplog no matter what size the vdisk is. If you get a very big vdisk and you do write operations towards it very actively, it might be performing slower, because the oplog would get full very quickly. The trick is to create multiple vdisks and present them to the guest OS. If the application cannot work with multiple disks and requires only 1 disk, you can use striped volumes to create a single guest disk made of multiple Nutanix vdisks. For example, if you need 4.5Tb, you can create 5x900Gb disks to get the same size, but that way you will get 5 times write cache compare to asingle large vdisk and the performance will be better. However, if performance is not very important, you can go with 1 large vdisk.