How many drives?

[Andy Green]

Somebody in the thread at some point said:
> 
>    What's a quick (even dirty) way of finding out how many HDs a system
> has?  Assuming that:
> 
>       a) Not all of them are actively used, so they wouldn't be in
>          /etc/fstab (or visible in df)
> 
>       b) /var/log/dmesg isn't available for scanning
> 
>       c) /var/log/messages isn't available for scanning
> 
>       d) And access to the boxes is (somewhat) restricted - they're in
> racks, and I really don't feel like yanking each and every one)
> 

Cool thing...

$ cat/proc/diskstats

lists unmounted stuff as well while the drive is still physically present.

-Andy