USB Drives

[Fan924]

You are limited to 4 IDE drives. Are there any limitations in the
number of USB drives?

[thoss]

At 23:48:34 on Thu, 20 Mar 2008 Fan924 opined:-

>You are limited to 4 IDE drives. Are there any limitations in the
>number of USB drives?

I would imagine the limit would be when you run out of letters of the
alphabet, so 23 if you have just one fixed partition. But that would be
only when you have all the USB drives connected at the same time.
--
Thoss

[Jeff Jonas]

>You are limited to 4 IDE drives. Are there any limitations in the
>number of USB drives?

There's no longer the "4 hard drive" limit on PCs.
My PC right here has 2: ATAPI (IDE) controllers on the motherboard,
each allows 2 drives, so that's 4 drives.
A PCI card adds 2: Serial ATA drives and 2: Parallel ATA drives,
for a total of 8.
USB adapters allow me to connect even more hard drives externally.

The real question is "what table or resource is exhausted first".
For DOS/Windows, drives are assigned a single letter
so A-Z is probably the first limit you'll hit
(unless there's some other table size restriction
such as number of USB devices active at one).
Linux allows mounting devices anywhere in the file tree,
so the mount table size is probably the limit.

There's the practical limit of number of USB connections since
USB does not allow cascading or daisy-chaining.
Each USB device must connect to a hub.
8 port USB hubs are available but the 4 port ones are most affordable.
A PC with 6 USB connectors, each to a 4 port hub would be 24 USB devices,
so that's achievable but silly.