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A SAN administrator recently installed a storage encryption switch on the Fibre Channel Fabric. Shortly after the deployment, several new VMFS5 datastores recently created were dismounted. Attempts to manually mount them fail. VMFS5 upgraded datastores are unaffected. All Storage arrays in use support VASA and VAAI.
What is the root cause of this problem?
A. All newly created VMFS5 datastores are tagged ATS_Only. The storage encryption switch blocks the ATS command.
B. All newly created VMFS5 datastores are tagged XCOPY_Only. The storage encryption switch blocks the XCOPY command.
C. All newly created VMFS5 datastores are tagged WRITE_SAME_Only. The storage encryption switch blocks the WRITE_SAME command.
D. All newly created VMFS5 datastores were formatted with 1MB block size. The storage encryption switch does not support this block size.
Correct Answer: A
Explanation/Reference:
Explanation:
A: When a VMFS-5 volume is formatted on a VAAI capable device, it uses ATS locking, which is termed as ATS-only. In other words; If a VMFS5 volume is unmounted and its device is detached, removed from an existing ESX server, and then presented to a new server (or presented back to the same server again), it fails to mount the VMFS5 volume. This means that the storage encryption on the switch will block the attempts to mount the datastore.
Incorrect Answers:
B: The XCOPY off load enables the storage arrays to make full copies of data within the array without having the host read and write the data. This will not prevent the mounting of the datastore.
C: The write same tag will enable storage arrays to zero out a large number of blocks to provide newly allocated storage, free of previously written data. This is not the reason why the datastore will not mount.
D: The block size formatting is not the problem since the issue arise only after it has been dismounted which means that the datastores did mount successfully prior to dismounting.
References:
http://kb.vmware.com/selfservice/microsites/search.do?
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