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Extending VMware volumes
55 Dell EMC SC Series: Best Practices with VMware vSphere | 2060-M-BP-V
13.1.2 Adding a new extent to an existing datastore
This legacy functionality was used with previous versions of vSphere to concatenate multiple volumes to
create VMFS-3 datastores larger than 2 TB. Since the maximum datastore size with VMFS-5 has been
increased to 64 TB, the use of extents is no longer necessary.
Caution: Due to the complexities of coordinating snapshots (replays) and recoveries of datastores that are
spanned across multiple SC Series volumes, the use of VMFS extents is highly discouraged. However, if the
use of extents is necessary, snapshots of those volumes should be taken using the consistent snapshot
schedule (replay profile) functionality.
13.2 Increasing the size of a virtual machine disk (VMDK) file
Hot extending a SCSI virtual disk is available from within the vSphere client when editing the settings of a
virtual machine.
Growing a virtual disk from the virtual machine properties screen
After growing the virtual disk from the vSphere client, an administrator must connect to the virtual machine,
rescan for new disks, and then extend the file system.
Caution: Microsoft does not support extending the system partition (drive C) of a machine in certain versions
of Windows.
13.3 Increasing the size of a raw device mapping (RDM)
To extend a raw device mapping, follow the same basic procedure as with a physical server. First, extend the
RDM volume from within the DSM Client, rescan disks from Windows disk management, and then use
DISKPART or the Storage MMC console to extend the drive.
A physical mode RDM whose placeholder VMDK resides on a VMFS-5 datastore can be extended up to the
64 TB limit. However, depending on the version, vRDMs may have a limit anywhere between 2 TB to 62 TB.
Caution: Like datastore volumes, it is also important not to extend an RDM volume with its pointer file
residing on a VMFS-3 datastore past the 2047 GB (1.99 TB) limit.