I was just answering some questions on the VMTN forum when someone asked the following question:
Should I upgrade our VMFS luns from 3.21 (some in 3.31) to 3.46 ? What benefits will we get?
This person was referred to an article by Frank Brix Pedersen who states the following:
Ever since ESX3.0 we have used the VMFS3 filesystem and we are still using it on vSphere. What most people don’t know is that there actually is sub versions of the VMFS.
- ESX 3.0 VMFS 3.21
- ESX 3.5 VMFS 3.31 key new feature: optimistic locking
- ESX 4.0 VMFS 3.33 key new feature: optimistic IO
The good thing about it is that you can use all features on all versions. In ESX4 thin provisioning was introduced but it does need the VMFS to be 3.33. It will still work on 3.21. The changes in the VMFS is primarily regarding the handling of SCSI reservations. SCSI reservations happens a lot of times. Creation of new vm, growing a snapshot delta file or growing thin provisioned disk etc.
I want to make sure everyone realizes that this is actually not true. All the enhancements made in 3.5, 4.0 and even 4.1 are not implemented on a filesystem level but rather on a VMFS Driver level or through the addition of specific filters or even a new datamover.
Just to give an extreme example: You can leverage VAAI capabilities on a VMFS volume with VMFS filesystem version 3.21, however in order to invoke VAAI you will need the VMFS 3.46 driver. In other words, a migration to a new datastore is not required to leverage new features!
Doug says
Great information — I have never been able to find this anywhere else.
I do have a question about one of the statements here:
“In ESX4 thin provisioning was introduced but it does need the VMFS to be 3.33. It will still work on 3.21”
Should the first sentence read, “In ESX4 thin provisioning was introduced but it does NOT need the VMFS to be 3.33?”
Doug says
Nevermind… I haven’t had enough coffee yet this morning and didn’t follow the quoting properly.
Rick Vanover says
I still think that if we can afford the time and I/O to migrate off and reformat; it should be considered.
Plus, that may be a good time to wipe out an 1, 2 or 4 MB block size datastores!
Duncan Epping says
Why would you when it doesn’t add anything?
Rick Vanover says
What if it does in the future, then I’m that much closer to right.
Again, “If I can do it with no impact”.
To be fair, I’ve only formatted upwards a handful of times. Block size is the primary reason, VMFS ver 2nd reason.
Brandon says
Are there any differences in the VMFS 3.x filesystem itself, or is it just a flag in the metadata that identifies this verion of the driver formatted this volume? From your post it looks like there are no changes at the filesystem level at all.
I think people get curious because when you look at the properties of a datastore, you see a “version” number there. I can see the purpose of that being in there, perhaps so you can see the version differences when there are major releases, ie. 2 -> 3.
Duncan Epping says
As far as I know the chances in the filesystem made are minimally and VMware internal only.
Ronald says
Can you elaborate a little on the differences with regard to the scsi reservations? Does it make a difference in production environments. Also, do you know the changes in 3.46? Further, great article, very useful to know that the driver is key.
Duncan Epping says
Difference for SCSI Reservations from 3.0 to 3.5 were huge as optimistic locking was introduced. It basically means that we combine several locks on a single host in a single combined batch to reduce overhead and decrease the “time”. This was even more improved when VAAI was introduced.
Ronald says
Thanks for the reply. So basically upgrading your VMFS from 3.21 to 3.31 would have benefit, when it comes to SCSI-reservations? And upgrading to 3.46 would be even more beneficial, if you can use VAAI?
Ronald says
Nevermind, just read the article (thoroughly this time ;)), and see that it is not.
djlaube says
Thanks Duncan for this post. However you don’t go into changing the VMFS driver? For example, I was onsite at a customer and they wanted to use thin-provisioning but their VMFS “version” was below the version that supported it. How do we fix that without migration to a new datastore? (which is what I did for them, using Storage vMotion)..
Many thanks! Cheers!
Duncan says
No, changing the VMFS driver is as simple as upgrading your ESXi host to the next release. There’s no need to do anything else.
HalChris says
The only question I have is why does the datastore show the formatting version if it doesn’t matter?
cgrvy says
What are the features that we can expect to see in the next version of VMFS?
Thoughts/wishes anyone?
Florian says
statement still correct using ESX5 but VMFS3?
“…a migration to a new datastore is not required to leverage new features!”
Duncan says
I cannot comment on any futures.
Srikanth Gopalachar says
Understand your position!
ela2014 says
hello
in my network i have vsphere server 4.1 and i want upgrade to 5.what happen if i want vmfs 3 upgrade to vmfs 5 for my VMs in vsphere?
Duncan says
Nothing happens to the VMs. It is a non-disruptive upgrade process.
Bals says
Is it possible to upgrade datastore alone from VMFS3.33 to VMFS 3.5 on vpshpere4.0 environment? if yes, how?
We are planning to use Lun>2TB in Vsphere4 environment.
Thanks in advance
Bals
Duncan Epping says
There is no such thing as VMFS 3.5.
Bals says
sorry, VMFS 5.
ela2014 says
already we have used vsphere 4 with cracked license and we have plane to upgrade to vsphere 5,meanwhile we have vsphere 5 cracked license .what problem
will be occur for license during upgrade from vsphere 4 to 5 ?
tnx all
Duncan says
Are you seriously asking me if I can help while you have a “cracked license” for vSphere? You do realize I am a VMware employee?
Troy says
@ela2014 ha ha ha what an awesome question.
Duncan maybe you can give him the answer but he will have to find a crack to be able to read it.
Mo says
@ela2014 – Why use a cracked license, when you can generate 60 days licenses via email address every two months. you will still be legal (for evaluations) and will be able to ask questions freely!
Nick says
Wondering if your assertion that: ‘All the enhancements made in 3.5, 4.0 and even 4.1 are not implemented on a filesystem level but rather on a VMFS Driver level or through the addition of specific filters or even a new datamover”, applies to ESx5i aswell?
For example after upgrading to ESX5i, do I need to upgrade my datastores to VMFS5 to get the benefits of >2tb datastores etc?
Duncan Epping says
Cormac Hogan wrote an excellent article on this topic: http://blogs.vmware.com/vsphere/2011/07/new-vsphere-50-storage-features-part-1-vmfs-5.html