Mathias Begert's questions

The mpstat utility reports CPU statistics. Where the first parameter specifies the interval like this (from mpstat man page):

The  interval parameter specifies the amount of time in seconds between each report.

Is there a way to define an interval less than one second like e.g. in sleep, there can be passed fractions of one second with sleep 0.2?

I am preparing for a certification and have a locally installed CentOS7 (VirtualBox) and another instance in a cloud-based service.

On the local system I have a /dev/sda and on the cloud-based i have a /dev/vda.

Now I am wondering what this difference exactly means? Is there a standard (documentation?) for the naming of this devices, and what the different names stand for?

Edit:

I think this document is very useful to understand the naming: https://www.kernel.org/doc/Documentation/admin-guide/devices.txt

8 block SCSI disk devices (0-15)
      0 = /dev/sda      First SCSI disk whole disk
     16 = /dev/sdb      Second SCSI disk whole disk
     32 = /dev/sdc      Third SCSI disk whole disk
        ...
    240 = /dev/sdp      Sixteenth SCSI disk whole disk

But I could not find some information about /dev/vda.