The current block size of a datastore in VMFS3 is 4MB. An administrator needs to upgrade the
datastore to VMFS5 and wants to change it to 1MB block size.
Which action should the administrator take?
A.
Upgrade the datastore to VMFS 5. Select the 1MB block size option during the upgrade.
B.
Create a new VMFS5 datastore with a 1MB block size. Migrate all virtual machines from the
existing datastore to the new datastore, then delete the VMFS3 datastore.
C.
Upgrade the datastore to VMFS5. Use vmkfstools to change the block size on the upgraded
datastore.
D.
Create a new VMFS5 datastore with a 1MB block size. Migrate all virtual machines from the
existing datastore to the new datastore. Upgrade the virtual machine hardware on the migrated
VMs, then delete the VMFS3 datastore.
http://www.vmware.com/files/pdf/techpaper/VMFS-5_Upgrade_Considerations.pdf
Confirmed answer.
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https://pubs.vmware.com/vsphere-55/index.jsp?topic=%2Fcom.vmware.vsphere.storage.doc%2FGUID-7D88E01D-360F-4215-8D0B-F2B8424E5F42.html
pgrading VMFS Datastores
If your datastores were formatted with VMFS2 or VMFS3, you can upgrade the datastores to VMFS5.
When you perform datastore upgrades, consider the following items:
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To upgrade a VMFS2 datastore, you use a two-step process that involves upgrading VMFS2 to VMFS3 first. Because ESXi 5.0 and later hosts cannot access VMFS2 datastores, use a legacy host, ESX/ESXi 4.x or earlier, to access the VMFS2 datastore and perform the VMFS2 to VMFS3 upgrade.
After you upgrade your VMFS2 datastore to VMFS3, the datastore becomes available on the ESXi 5.x host, where you complete the process of upgrading to VMFS5.
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You can perform a VMFS3 to VMFS5 upgrade while the datastore is in use with virtual machines powered on.
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While performing an upgrade, your host preserves all files on the datastore.
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The datastore upgrade is a one-way process. After upgrading your datastore, you cannot revert it back to its previous VMFS format.
An upgraded VMFS5 datastore differs from a newly formatted VMFS5.
Comparing Upgraded and Newly Formatted VMFS5 Datastores
Characteristics
Upgraded VMFS5
Formatted VMFS5
File block size
1, 2, 4, and 8MB
1MB
Subblock size
64KB
8KB
Partition format
MBR. Conversion to GPT happens only after you expand the datastore to a size larger than 2TB.
GPT
Datastore limits
Retains limits of VMFS3 datastore
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Considerations – Upgrade or Create New
While a VMFS-3 which is upgraded to VMFS-5 provides you with most of the capabilities as a newly created VMFS-5, there are some differences. Both upgraded and newly created VMFS-5 support single-extent volumes up to 64TB and both support VMDK sizes of ~2TB, no matter what the VMFS file-block size is. However additional differences, although minor, should be considered when making a decision whether to upgrade to VMFS-5 or create new VMFS-5 volumes.
No Uniform Block Size
VMFS-5 upgraded from VMFS-3 continues to use the previous file-block size, which may be larger than the unified 1MB file-block size. This can lead to stranded/unused disk space when there are lots of small files on the datastore.
No New Sub-Block Size
VMFS-5 upgraded from VMFS-3 continues to use 64KB sub-blocks and not the new 8KB sub-blocks. This can also lead to stranded/unused disk space. The upgraded VMFS-5 also continues to use the original number of sub-blocks from the VMFS-3.
No Increase to the Maximum Number of Files per Datastore
VMFS-5 upgraded from VMFS-3 continues to have a file limit of 30,720 rather than new file limit of > 100,000 for newly created VMFS-5. This has an impact on the scalability of the file system.
Uses MBR
VMFS-5 upgraded from VMFS-3 continues to use MBR (Master Boot Record) partition type; when the VMFS-5 volume has grown beyond 2TB, it automatically and seamlessly switches from MBR to GPT (GUID Partition Table) with no impact on the running virtual machines.
Starts on Sector 128
VMFS-5 upgraded from VMFS-3 continues to have its partition starting on sector 128. Newly created VMFS-5 partitions will have their partition starting at sector 2048.
VMware vSphere VMFS-5 Upgrade Considerations
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