[CentOS] 64 bit hardware and filesystem size limit

Tue Aug 23 15:38:12 UTC 2005
Sean Staats <sstaats at questia.com>

Thank you for your response, Bryan.  It appears that the 3Ware card is
reporting the disk array size correctly.  I've now created 2 arrays on
the controller - one is 1999.9 GB (/dev/sda) and the other is 2499.9 GB
(/dev/sdb) as reported by 'fdisk -l':

[root at anchor ~]# fdisk -l /dev/sda
 
Disk /dev/sda: 1999.9 GB, 1999957393408 bytes
255 heads, 63 sectors/track, 243147 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
 
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1      243147  1953078246   83  Linux

As you can see, /dev/sda1 uses all 243147 cylinders.

Unfortunately, when creating /dev/sdb1, only the first 36585 of 303934
cylinders can be used:

[root at anchor ~]# fdisk /dev/sdb
<snip>
Command (m for help): p
 
Disk /dev/sdb: 2499.9 GB, 2499946741760 bytes
255 heads, 63 sectors/track, 303934 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
 
   Device Boot      Start         End      Blocks   Id  System
 
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-36585, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-36585, default 36585):
Using default value 36585

It appears to me that the 3Ware card is reporting the information
correctly, but fdisk is having the trouble.  Is this due to running
32-bit software?  Do you think running on 64-bit hardware and 64-bit
CentOS will fix this problem?

Many thanks.
-Sean

On Mon, 2005-08-22 at 17:46, centos-bounces at centos.org wrote:
> On Mon, 2005-08-22 at 17:35 -0500, Sean Staats wrote:
> > We recently bought a 32-bit Xeon system with a 12-port 3Ware RAID card
> > and a dozen 500GB drives.  We wanted to create 4TB drive arrays;
> > however, we soon discovered that there is about a 2.2TB drive array size
> > limit on 32-bit hardware.  Does that sound correct?
> 
> Yes, 2^40 = 2TiB ~ 2.2TB (2.2 * 10^12).  This is a PC geometry issue,
> although Linux can get around it.
> 
> > Would replacing the 32-bit mobo/cpu with a 64-bit mobo/cpu allow us to
> > use drive arrays larger than 2.2TB?
> 
> Actually it's a 3Ware question because 3Ware has an intelligent ASIC on-
> board.  It's driving the disk array, not Linux.  It's merely presenting
> the disk array as a block, and Linux talks to the ASIC, not the disks.
-- 
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| Sean Staats      Systems Administrator, Developer
| Questia Media, Inc.               http://www.questia.com
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|"Linux - World domination. Fast."        --Linus Torvalds
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