The Linux 64 GiB Limit - was: Re: oops! Should be fdisk broken?

Guest section DW (dwguest@win.tue.nl)
Mon, 25 Jan 1999 23:26:48 +0100 (MET)

> From: David Hamm <dhamm@itserve.com>
>
> I have an 84g raid unit I'm trying to fdisk. When the computer boots I get
> the following info on the drive.
> SCSI device sdb: hdwr sector= 512 bytes. Sectors= 164659200 [80400 MB] [80.4 GB]
> When I fdisk it I get different info and after partitioning and mke2fs the
> dirve only mounts with 14g of space. I know this is a geometry issue but why
> is it an issue? Can fdisk be fixed?
>
> Not if you do not provide any detail at all.

From dhamm@itserve.com Mon Jan 25 16:48:31 1999
From: David Hamm <dhamm@itserve.com>

Disk /dev/sdb: 64 heads, 32 sectors, 14864 cylinders

Aha! Very good. You lost precisely 2^27 sectors, that is 64 GiB,
or, more relevant, 2^16 cylinders.

No surprise, since cylinders is a short.

So, the following should improve things. (Unverified, untested.)

Andries

--- hdreg.h~ Fri Jan 22 16:49:34 1999
+++ hdreg.h Mon Jan 25 23:13:06 1999
@@ -114,7 +114,7 @@
struct hd_geometry {
unsigned char heads;
unsigned char sectors;
- unsigned short cylinders;
+ unsigned long cylinders;
unsigned long start;
};

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