Re: lots and lots of disks again

Matthew Wilcox
2004-02-17T15:28:20Z

On Tue, Feb 17, 2004 at 08:57:24AM +0100, Kurt Garloff wrote:
> OK, if you take care to register some major number (or some space for
> dev_t in newspeak), I'll write the patch to allow the SCSI disks to
> be registered there. We need about 20 bits, IMHO.

20 bits might not be quite big enough. Assuming 6 bits for partitions,
that gives us 14 bits (16384 devices). I'd like a fibrechannel person
to chime in here and tell us about the biggest FC array they've ever
seen, but given multipathing showing us the same device multiple times,
that seems a little tight (given how much pain it is to move to a new
numbering scheme).

If we're talking about the numberspace for /dev/drive, I don't see why
we shouldn't take a quarter of the space; ie 2^30 bits. I suggest we
take 64.0.0.0/30 to leave the top half unused for now.

--
"Next the statesmen will invent cheap lies, putting the blame upon
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince
himself that the war is just, and will thank God for the better sleep
he enjoys after this process of grotesque self-deception." -- Mark Twain