VMFS-5–what you need to know in a nutshell….

It’s new, and it’s good :-)

• VMFS-5 increases limits (without increasing extents) to 64TB. 
• It enables 2TB+ RDMs. 
• It uses a common allocation size of 1MB.
• It increases the small block allocations available for total use.
• It is a dependency for SCSI UNMAP
• It uses the VAAI HW accelerated locking more extensively.

A couple things that it doesn’t do:

1. Increase the maximum LUN counts.   Although frankly, with the fact that people should be using larger datastores with VAAI and VMFS-5, that should help with this.
2. While it can non-disruptively be upgraded from VMFS-3 to VMFS-5 – this doesn’t net you all the goodness.  IMO, if it were my environment – I would tend to create new datastores and svmotion.   If I were large, I would still do it that way – but would do it programmatically.

Comments

[Jon Kohler]

What is left out during the upgrade from VMFS3 to VMFS5?

Also, what happens if you have over 1MB blocks on VMFS3 now?

As I am not familiar with the SCSI UNMAP command, are there any arrays that will not support this (on the EMC side)?

Thanks,
@JonKohler

[Mtellin]

Good info, can you expand on the VMFS 3 to VMFS 5 upgrade and not getting all the goodness?

[eprich]

From what I saw, if you upgrade a VMFS3 vol to a VMFS5 vol, the original block size remains the same.

[Rickard Nobel]

>Also, what happens if you have over 1MB blocks on VMFS3 now?

From my understanding, the old blocksize will be left if doing an upgrade.

[Paul Henry]

What is left out when you upgrade?

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.
VMFS-5 upgraded from VMFS-3 continues to use 64KB sub-blocks and not new 8K sub-blocks.
VMFS-5 upgraded from VMFS-3 continues to have a file limit of 30720 rather than new file limit of > 100000 for newly created VMFS-5.
VMFS-5 upgraded from VMFS-3 continues to use MBR (Master Boot Record) partition type; when the VMFS-5 volume is grown above 2TB, it automatically & seamlessly switches from MBR to GPT (GUID Partition Table) with no impact to the running VMs.
VMFS-5 upgraded from VMFS-3 continue to have its partition starting on sector 128; newly created VMFS5 partitions will have their partition starting at sector 2048.

Best;

Paul

[nipester]

It would have been nice if they'd addressed the block misalignement bug for various Oses. Oh well, maybe in 2020.