After attaching a ISCSI target to ESXi 4.1 U1, we saw that ESXi created a 740,25 GB partition onto the LUN, even though the device has 2,7 TB capacity. Why did ESXi not create a bigger vmfs partition? How to fix it?

  • We tried deleting the partition from storage server with cfdisk and letting ESXi recreate the partition using a different blocksize but this resulted the partition size to still be 740 GB. – Henno Apr 27 '11 at 13:22
  • Updated the question with new information about ESX LUN limits. – Henno Apr 27 '11 at 13:52
  • Relocated the information from question to answer part. – Henno Apr 27 '11 at 13:57

The "Why?" part:

According to http://www.delltechcenter.com/page/3TB+drives%3A+OS+Behavior+Matrix, the maximum LUN size for VMFS is 2TB.

According to http://www.delltechcenter.com/page/3TB+drives%3A+OS+Behavior+Matrix what ESX will do if the LUN size is bigger is it makes a 740GB partition and the rest is inaccessible.

The "How to fix it" part:

Present a smaller than 2TB LUN to ESX. That can be done by creating partitions on the disk (/dev/sdb1 /dev/sdb2) and exporting those partitions as separate LUNs to ESX.


Max size LUN in ESXi is 2TB -512 Bytes. The LUN can be no bigger. The information can be found in the VMware configurations maximums document.

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