I have found some VM appliance with CPU share value 1. What does it mean ? Is it lowest possible value (or 0 is lowest)?
Maximum is 1000000. It is some VM appliance with default values, but I think that sth is wrong here - it should be at least set to normal share, which is 1000 - Am I right ?
I know that for some hypervisors value 1 means unlimited or max, but probably not for vmware.
That reservation of 2596 with a single vCPU means that the VM will only experience any CPU contention above 2596MHz, that's the only time the shares would have any meaning.
The default CPU shares are 1000 per vCPU, but I'd guess the same admin who set the reservation also deliberately modified the shares.
If your host CPU is 2596MHz anyway, modifying the shares will have no effect with that reservation value.
That reservation of 2596 with a single vCPU means that the VM will only experience any CPU contention above 2596MHz, that's the only time the shares would have any meaning.
The default CPU shares are 1000 per vCPU, but I'd guess the same admin who set the reservation also deliberately modified the shares.
If your host CPU is 2596MHz anyway, modifying the shares will have no effect with that reservation value.