Can't create a partition beginning at sector 1

fakie_flip · 06-12-2012, 05:49 AM

I would like to know what's preventing me from creating a partition beginning at sector 1 and how I can do it. This never had been an issue before. Thanks.

Code:

Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00030f12

   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, default 1): 1
First sector (2048-78140159, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-78140159, default 78140159): 
Using default value 78140159

Command (m for help): p

Disk /dev/sda: 40.0 GB, 40007761920 bytes
255 heads, 63 sectors/track, 4864 cylinders, total 78140160 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00030f12

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    78140159    39069056   83  Linux

Command (m for help): d
Selected partition 1

Command (m for help): d
No partition is defined yet!

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4, default 1): 1
First sector (2048-78140159, default 2048): 1
Value out of range.
First sector (2048-78140159, default 2048):

thorkelljarl · 06-12-2012, 05:57 AM

Alignment I believe...

http://superuser.com/questions/35257...-instead-of-63

Do you need the space?

fakie_flip · 06-12-2012, 06:02 AM

Quote:

Originally Posted by thorkelljarl

Alignment...

http://superuser.com/questions/35257...-instead-of-63

The link talks about a user that needs his partitions aligned on two drives for use with RAID1. I'm using a laptop with a single drive.

pixellany · 06-12-2012, 06:03 AM

The first sector is for the bootloader, primary partition table, etc.---so you can't start a partition there. I think that starting the first partition at sector 2048 is pretty common. ((I think)) that sectors 2 thru 2047 are sometimes used for boot code and other "overhead" functions.

thorkelljarl · 06-12-2012, 06:07 AM

Not only about RAID...

It was this that I found relevant.

Quote:

Because your old disc was partitioned with a old utility, such as the Linux fdisk, that uselessly implemented track-alignment using the entirely fake disc geometry that you see reported, and your new disc has been or is being partitioned by a newer utility that (by default) aligns to 1MiB boundaries instead.
Further reading

Jonathan de Boyne Pollard (2011). The gen on disc partition alignment. Frequently Given Answers.

link|improve this answer

answered Oct 31 '11 at 23:21
JdeBP
8,1851024

In other words, the LBA sector number 63 corresponds to cylinder 0, head 1, sector 1 in the CHS format, which is the first sector you can use in the MBR format. However, the number 63 is not divisible by 8, which causes a problem with 4K drives, so some modern tools starts the first partition at 2048 which also provides future GPT compatibility. – billc.cn Oct 31 '11 at 23:48

thorkelljarl · 06-12-2012, 06:15 AM

By the way...

This subject in general has the complexity of the tax codes of several of the worlds most developed nations and is something that in former times contributed to perpetuating the practice of dueling.

syg00 · 06-12-2012, 06:40 AM

I would doubt you ever allocated partition(s) from sector one (zero based counting pixellany).
Cylinder one I would accept as plausible.

As discussed above megabyte alignment is now accepted as "normal"

pixellany · 06-12-2012, 11:01 AM

Quote:

Originally Posted by syg00

.....from sector one (zero based counting pixellany)......"

ooopppsss!!

fakie_flip · 06-12-2012, 04:23 PM

Ok, I've been compiling software in Gentoo now for at least an hour now. Once this distcc is finished and setup, everything else should be fast.