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In VMware vSphere there was an hystorical limit of VMDK disks around 2 TB (2 TB – 512 B), but the real “usable” was also less due to the need to make a snapshots on it (if you want use native backup solutions) and depending on the block size (for more informations see Veeam KB 1091).
Starting with vSphere 5.5 was finally possibile have bigger disks up to 62 TB (that I will call just “jumbo” disks), but again with several limits describe in VMware KB 2058287 (Support for virtual machine disks larger than 2 TB in VMware ESXi 5.5.x and 6.0.x):
- Only ESXi 5.5 or greater is supported
- VMFS-3 volumes are not supported. You cannot move disks greater than 2 TB from a VMFS-5 datastore to a VMFS-3 datastore.
- The maximum supported VMDK size on an VMFS-5 datastore is increased to 62 TB. However, the maximum supported VMDK size on VMFS-3 is still 2 TB.
- The maximum supported size of a VMDK on NFS is the lesser of 62 TB and 1% less than the maximum file size supported by the NFS filesystem. The largest file size depends on the underlying file system (for example, 16 TB on ext3).
- Fault Tolerance is not supported.
- BusLogic parallel controllers are not supported.
- vSphere Flash Read Cache supports a maximum hard disk size of 16 TB
- vSphere Client has got some limitations in the size of the disks (after 4TB) and jumbo disks must be managed by the Web Client (or the Host Web Client)
But not only: initially was not possible hot-add a jumbo disk to a running VM, in this was, for example, backup using virtual appliance transport mode (or hot-add mode) was not possible at all.
And was not possible hot-add new space to a running VM with this error:
Hot-extend was invoked with size (*** sectors) > =2TB. Hot-extend beyond or equal to 2TB is not supported. This disk extend operation failed: msg.disklib.INVAL
So, in vSphere 5.5 or 6.0 you cannot hot-extend a virtual disk if the capacity after extending the disk is equal to or greater than 2 TB. Only offline extension of GPT-partitioned disks beyond 2 TB is possible.
Finally in vSphere 6.5 it’s now possible pass this limit (see this post) and hot-add space also to jumbo disks.
But please note that guest OS must also support those disks. For example to enable the Microsoft Windows operating system to address a maximum storage capacity for a device greater than 2 TB, the disk must be initialized by using the GUID partition Table (GPT) partitioning scheme. For more information, see Windows support for hard disks that are larger than 2 TB.