How to change LBA48 addressing capability

Dan Hensley dan at dshensley.com
Tue Jul 8 02:59:12 UTC 2008


I recently sent an inquiry to this list about fdisk being unable to seek
one of my two basically identical disks.  Both are Western Digital 250Gb
disks.

Unable to seek on /dev/sdb

This disk operates just fine when booting Fedora Core 6.  However, as
soon as I boot Fedora 9, I get the above error.  testdisk seems to
think /dev/sdb is only 137gb, and hdparm confirms something strange.

Here is the output from /dev/sda, which is operating correctly in Fedora
9:

[root at amd64 ~]# hdparm -I /dev/sda

/dev/sda:

ATA device, with non-removable media
	Model Number:       WDC WD2500JS-00MHB0                     
	Serial Number:      WD-WCANK1038714
	Firmware Revision:  02.01C03
Standards:
	Supported: 7 6 5 4 
	Likely used: 8
Configuration:
	Logical		max	current
	cylinders	16383	16383
	heads		16	16
	sectors/track	63	63
	--
	CHS current addressable sectors:   16514064
	LBA    user addressable sectors:  268435455
	LBA48  user addressable sectors:  488397168
	device size with M = 1024*1024:      238475 MBytes
	device size with M = 1000*1000:      250059 MBytes (250 GB)


Here is the output from /dev/sdb:

[root at amd64 ~]# hdparm -I /dev/sdb

/dev/sdb:

ATA device, with non-removable media
	Model Number:       WDC WD2500KS-00MJB0                     
	Serial Number:      WD-WCANKC798286
	Firmware Revision:  02.01C03
Standards:
	Supported: 7 6 5 4 
	Likely used: 8
Configuration:
	Logical		max	current
	cylinders	16383	16383
	heads		16	16
	sectors/track	63	63
	--
	CHS current addressable sectors:   16514064
	LBA    user addressable sectors:  268435455
	LBA48  user addressable sectors:  268435455
	device size with M = 1024*1024:      131071 MBytes
	device size with M = 1000*1000:      137438 MBytes (137 GB)



Why is the LBA48 size not the same for both disks, and how can I correct
this?

Dan







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