parted 1.6.5 problem with _very_ large disk

[Anders Lennartsson]

Hi

I have encountered problems with partitioning a device on a raidcard,
3ware 7500-8 with a raid-5 configuration on 8x185.2GB IBM disks. This
leaves 7x185GB net, reported as 2533145216 sectors of 512 byte each by
fdisk, or a total of 1296970350592 bytes :D

While fdisk did the job of creating one ext3 partition on this device, I
also tried parted, from Debian Testing where parted is at version
1.6.5-1.

Here is the output from just starting parted: (c/h/s are exactly as
fdisk reports them)



abbott:~# parted /dev/sdc      
GNU Parted 1.6.5
Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation,
Inc.
This program is free software, covered by the GNU General Public
License.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

Using /dev/sdc
Information: The operating system thinks the geometry on /dev/sdc is
157680/255/63.  Therefore, cylinder 1024 ends at 8032.499M.
(parted)




Here is the output from print in parted:

abbott:/home/skalman# parted /dev/sdc print
Disk geometry for /dev/sdc: 0.000-1236887.312 megabytes
Disk label type: msdos
Minor    Start       End     Type      Filesystem  Flags
1          0.031 -860272.508  primary   ext3        
Information: Don't forget to update /etc/fstab, if
necessary.             



I think, without actually checking the code, that the minus sign comes
from using signed integers (32bit) because the number of sectors is more
than 2^31 (but less than 2^32) which results in a negative number if
signed int is used. Two possible ways out, change to unsigned or go up
to long long, where necessary.



Interesting is also that the documentation for the 3ware card says that
there is a limit of some 2TB and the 3ware bios will not configure
devices bigger than that. This must be due to the fact that the
limitation of the partition table of 32-bits for start and end sector,
respectively, and 512-byte sectors, give a maximum size of 0xFFFFFFFF
times 512, or (when subtracting the 62 traditionally "empty" sectors at
the beginning of a disk) 2,199,023,223,296 bytes raw data.



Anders


PS the server is not put to use yet, so if you want to I might be able
to run some tests with modified versions of parted. During the following
weeks I'll sometimes be slow in response though. Vacation :)