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darmstrongnavig
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Error creating datastore on iSCSI LUN (EMC CX4/120)

I am running into an error when trying to create a datastore on a Clariion CX4/120.  The connectivity to the SAN is done through iSCSI.  I have successfully exposed the target to the storage adapter and it shows up in  Configuration > Storage Adapters > vmhba33 > Details.  It has a capacity of 5.37 TB.

When I go into Configuration > Storage and select Add Storage... , I can select Disk/LUN.  The LUN shows up there as well.  When I click Next, it populates the Device and Location information, and also reports "The hard disk is blank."  After about ten minutes it generates the following error...

Call "HostDatastoreSystem.QueryVmfsDatastoreCreateOptions" for object "ha-datastoresystem" on ESXi "172.20.100.78" failed.

I have done some Google searches and looked around here on the VMware site, and I cannot find any references to that error.  Are there any log files for the process that I can look into?  Do I need to engage EMC and see if this is an issue with the SAN itself?

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a_p_
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It has a capacity of 5.37 TB.

The limit for VMFS datastores is 2 TB minus 512 bytes. Try presenting smaller LUN's then it should work.

André

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a_p_
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It has a capacity of 5.37 TB.

The limit for VMFS datastores is 2 TB minus 512 bytes. Try presenting smaller LUN's then it should work.

André

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darmstrongnavig
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That was the issue.  I had read about data store size limitations, but when the software recognized it at 5.37 TB, I thought it would work.

If any VMware employees read this, a more helpful error message would be nice.

Andre, I've read that it is possible to increase the size of the LUN after it has been connected to the ESX server.  What do you think about that?

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a_p_
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There are two ways to increase the size of a datastore.

1.) Growing a datastore

This is comparable to "diskpart extend" in Windows. You can increase the size of a LUN up to the ~2TB limit and grow the VMFS datastore using the wizard.

2.) Using Extents

Before ESX 4.x the only way to increase the size of a datastore was to present a new LUN to a host and - instead of creating a dedicated VMFS datastore on it - extend an existing datastore. This is still possible and the max. size of an extended VMFS datastore can be ~64TB (32 extents), however unless there is a special need, this does not make any sense IMO. The disk space on an extended datastore will not be used evenly across all the extents and therefore you will have less performance than using multiple smaller datastores. In addition to this, the max. virtual disk (vmdk) size is still limited to ~2TB.

André

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