Hello team -
Finally had a chance to setup the NFS Server/Client and get my ESXi host mounting a NFS Datastore on my Ubuntu Box.
However, when I start a backup, I get the following error.
Destination disk format: VMFS thin-provisioned
Cloning disk '/
CLVMKFS1 error: Failed to clone disk: Input/output error (327689)
CLVMKFS1 error: Failed to clone disk: the file already exists (39)
This error: Input/output error (327689) denotes a problem in the transport layer, namely the NFS protocol. It could be caused by faulty hardware (bad disk?), or a bad NFS configuration. Re-check all permissions for the user you use, as it looks that XSIBackup is able to create the file but it can't go any further.
I have a similar error with 2 windows 8.1 VMs which will will make one VM will make it to 75% done, and the other to about 47% done because it gives the " Failed to clone disk: Input/output error (327689)" in the log.
This is with a cold backup.
The VMs otherwise boots and works fine.
How to diagnose what is wrong and remedy it?
As already stated, this type of error Failed to clone disk: Input/output error has to do with some uncontrolled condition at the hardware or transport layer: full disk, bad cable, bad disk, broken driver, etc...
Input/output error is an NFS error. NFS v3 works in ESXi out of the box, nevertheless, if you use NFS 4.1, ESXi might allow you to mount the NFS share, even though the transport layer may not be working properly. This situation leads some users to think their NFS share is working and blame some other part of their system.
To troubleshoot this:
1. First of all try to copy some file to your NFS share manually. You will then get the same error, this will note that the problem is at the storage protocol level, and has nothing to do with the application level.
2. Read your NAS or NFS server documentation. Most manufacturers publish information on how to configure it properly to be used with VMware ESXi hypervisor.
3. Please, do note that using NFS 4.1 to attach a backup device is useless. There is the common missconception that multipathing and other forms of link aggregation will sum the bandwith of all available NICs, when it does not work that way. A single file is always transmitted through a single path or NIC.
So, use NFS 3 for your backups and leave NFS 4.1 for your production environment, where having multipathing and multiple NICs available will be a great asset.