[CentOS] 64 bit hardware and filesystem size limit
Sean Staats
sstaats at questia.com
Tue Aug 23 15:38:12 UTC 2005
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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