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From: Douglas Gilbert <dougg@torque.net>
To: Bryan Henderson <hbryan@us.ibm.com>
Cc: Jeff Garzik <jeff@garzik.org>,
	Jan Engelhardt <jengelh@linux01.gwdg.de>,
	linux-fsdevel@vger.kernel.org,
	Linux-ide <linux-ide@vger.kernel.org>,
	linux-scsi <linux-scsi@vger.kernel.org>,
	Ric Wheeler <ric@emc.com>
Subject: Re: impact of 4k sector size on the IO & FS stack
Date: Mon, 12 Mar 2007 15:16:07 -0400	[thread overview]
Message-ID: <45F5A6F7.9080108@torque.net> (raw)
In-Reply-To: <OFCF49F323.33FDF27D-ON8825729C.0064FD4B-8825729C.0065C420@us.ibm.com>

Bryan Henderson wrote:
>> DOS partitions start partitions on odd-numbered sectors
> 
> I don't get this.  If you mean partitions defined by the classic DOS 
> partition table format, then AFAICS, such a partition can start in any 
> sector.

Bryan,
Typically the first partition on a DOS partitioned disk
starts at the next available sector after the mbr
which, for some bizarre reason, is 63 sectors long.
Hence:

# fdisk -lu /dev/hda

Disk /dev/hda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *          63    18314099     9157018+   c  W95 FAT32 (LBA)
/dev/hda2        18314100    19551104      618502+  82  Linux swap / Solaris
/dev/hda4        19551105   156296384    68372640   83  Linux


> 
>> so presuming you have odd-aligned disks, life is good.
> 
> What is an odd-aligned disk?

s/disk/partition/ ?
Perhaps hda1 and hda4 above are examples.

Doug Gilbert


  parent reply	other threads:[~2007-03-12 19:16 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-11 22:51 impact of 4k sector size on the IO & FS stack Ric Wheeler
2007-03-11 23:14 ` Jan Engelhardt
2007-03-12  2:45   ` Ric Wheeler
2007-03-12  3:27     ` Jan Engelhardt
2007-03-12  3:46       ` Andreas Dilger
2007-03-12 12:17       ` Alan Cox
2007-03-12 14:41       ` Jeff Garzik
2007-03-12 14:36   ` Jeff Garzik
2007-03-12 15:45     ` Alan Cox
2007-03-12 18:31     ` Bryan Henderson
2007-03-12 18:37       ` Sergei Shtylyov
2007-03-12 20:52         ` Bryan Henderson
2007-03-12 19:16       ` Douglas Gilbert [this message]
2007-03-12 19:28         ` Jeff Garzik
2007-03-12  0:02 ` Alan Cox
2007-03-12  0:44   ` Jeff Garzik
2007-03-12  2:37     ` Ric Wheeler
2007-03-12 12:24     ` Alan Cox
2007-03-12 13:32       ` Ric Wheeler
2007-03-12 15:21         ` Douglas Gilbert
2007-03-12 16:08           ` Martin K. Petersen
2007-03-12 14:26       ` Jeff Garzik
2007-03-13  5:11         ` Andreas Dilger
2007-03-13  6:34           ` Chris Wedgwood
2007-03-12  2:41   ` Ric Wheeler
2007-03-12  8:18 ` Christoph Hellwig
2007-03-12 14:40   ` James Bottomley
2007-03-12 14:45   ` Jeff Garzik
2007-03-12 14:57     ` Christoph Hellwig

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