How to change blocksize (file size limit) on VMFS3 filesystem
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In VMware ESX 3.5.x running VMFS3 filesystem there is limitation on file size which results in error if you are trying to create Guest virtual machine with large disk drive. For example if you are trying to create a guest VM with disk drive size larger than 256 you will get this error :
File is larger than the maximum size supported by datastore.
This happens because by default VMware ESX running VMFS3 uses 1M blocksize with a limitation of 256 GB disk size for the guest virtual machine. However it is possible to change or rather increase the size of disk drive that you can create for the virtual machine. If you can change block size to 2M on VMFS3 filesystem on your ESX server you can create disk drive upto 512GB size for the virtual machine.VMware Recommends following block size to create large disk drive on virtual machines :
1M Block Size max VMFS-3 = 256G
2M Block Size max VMFS-3 = 512G
4M Block Size max VMFS-3 = 1024G
8M Block Size max VMFS-3 = 2048G
File size larger than 2048 GB is not supported on VMFS3 filesystem, using VMFS2 you can go upto 16 M block size but that option is not available on VMFS3 filesystems.To changethe block size on a VMFS3 filesystem you can use vmkfstools command from command line ro reformat the parition. The vmkfstools command can be run on ESX server :
#vmkfstools –create vmfs3 –blocksize 2M vmhba1:0:0:2
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Jake said:
This syntax didn’t work…at least not for changing the block size for a local partition on an ESX host running ESX 3.5 Update 4. Kept giving me an error (may have simply been a capital “M” instead of lower case in the block size.) This one below worked correctly for me.
vmkfstools -C vmfs3 -b 2m -S LocalHDD vmhba0:0:0:3
where
-C creates the volume
-b sets the block size
-S sets the volume labelJune 17th, 2009 at 10:35 am
