Cannot create a VMDK with size greater than 600GB on NFS storage

[showmanlkz]

Hi guys,

My institue has been using vSphere ESXi 4.1U2 with vCenter 4.1 with the BlueArc based NFS storage. Recently I tried to create a VM with a 900GB disk. But the operation failed saying there is Input/ouput error. From the hostd.log, I found:

~ # cat /var/log/vmware/hostd.log | grep gagri

      snapshotDirectory = "[gagri_10G_VMPool01]",

[2012-05-11 14:27:07.431 21F40B90 info 'VmDiskMgr' opID=D2819F21-0003B52F-30] For disk [gagri_10G_VMPool01] New Virtual Machine/New Virtual Machine.vmdk, Error creating disk: Input/output error

I have done several tests and found that any size below 600GB is fine.

Later, I SSH to the ESXi host directly and tried to created a 900GB VMDK via vmkfstools, surprisingly, it's created without an error.

So I am wondering if there is bug with the vCenter??

Regards,

Derrick

[UmeshAhuja]

Hi,

What block size you have set while creating the datastore on ESXi host? , There might be less block szie set for the datastore from where you are trying to create the vmdk.

Kindly check with you datastore block size as per the below table requirement.

Block Size	Largest virtual disk on VMFS-2	Largest virtual disk on VMFS-3	Largest virtual disk on VMFS-5
1MB	456GB	256GB	2TB minus 512B
2MB	912GB	512GB	Valid if upgraded from VMFS-3
4MB	1.78TB	1TB	Valid if upgraded from VMFS-3
8MB	2TB	2TB minus 512B	Valid if upgraded from VMFS-3
16MB	2TB	Invalid block size	Invalid block size
32MB	2TB	Invalid block size	Invalid block size
64MB	2TB	Invalid block size	Invalid block size

Note: VMFS-5 has a maximum virtual disk size of 2TB minus 512B. However, passthrough RDMs are supported up to 64TB.

How to check Block size ?

Go to VI/vSphere Client:

1. Select an ESX host that contains the datastore.
   
2. Click the Configuration tab.
   
3. Click Storage.
   
4. Select the datastore.
   
5. The block size is identified in the Details window under the Formatting subheading.
   

[rickardnobel]

Umesh wrote:

What block size you have set while creating the datastore on ESXi host?

Since this was NFS storage there is no VMFS and by that no VMFS block size that will affect the size of VMDK files.

[aravinds3107]

With ESXi 4.1 Update1 we had fix for creating 1 TB of VMDK on NFS. May be you can check the below parameter if this helps

Creation of large .vmdk files on NFS might fail
When you create a virtual disk (.vmdk file) with a large size, for example, more than 1TB, on NFS storage, the creation process might fail with an error: A general system error occurred: Failed to create disk: Error creating disk. This issue occurs when the NFS client does not wait for sufficient time for the NFS storage array to initialize the virtual disk after the RPC parameter of the NFS client times out. By default the timeout value is 10 seconds. This fix provides the configuration option to tune the RPC timeout parameter using the esxcfg-advcfg -s <Timeout> /NFS/SetAttrRPCTimeout command.

[showmanlkz]

Hi,

This seems to be very relevant. I will try it out as soon as I am back to work next week and report back.

Cheers,

Derrick

Sent from my iPhone