maemo.org - Talk - View Single Post - sfdisk warnings ? any risk ?

sacal	2010-12-16 , 11:45
Posts: 165 \| Thanked: 78 times \| Joined on Jun 2010	#1

I did search maemo.org and googled, read a lot of posts but i am still confused and worried.
So i ask and thank for the advised opinions of this community.

Some days ago i repartitioned my N900 EMMC using gparted running in my linux desktop pc with my N900 in USB storage rd mode.

I follow the solution #6 in wiki.maemo.org/Repartitioning_the_flash and everything went fine. Gparted did move and resize the partitions and all my data was preserved.

After reboot all my installed applications and also multiboot / nitroid and powerkernel oc are working as before without any problem.

What i don't like

are the warnings that sfdisk reports:

Code:

sfdisk -l

Disk /dev/mmcblk0: 977024 cylinders, 4 heads, 16 sectors/track
Warning: The partition table looks like it was made
  for C/H/S=*/64/32 (instead of 977024/4/16).
For this listing I'll assume that geometry.
Units = cylinders of 1048576 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/mmcblk0p1          0+  21503   21504-  22020064    c  W95 FAT32 (LBA)
		start: (c,h,s) expected (0,2,1) found (1,0,1)
/dev/mmcblk0p2      21504   25599    4096    4194304   83  Linux
/dev/mmcblk0p3      25600   26367     768     786432   82  Linux swap / Solaris
/dev/mmcblk0p4      26368   30463    4096    4194304   83  Linux 

sfdisk -g
/dev/mmcblk0: 977024 cylinders, 4 heads, 16 sectors/track

sfdisk -G
/dev/mmcblk0: 30532 cylinders, 64 heads, 32 sectors/track

As i understand sfdisk detects that the disk geometry reported by the kernel (977024 cylinders, 4 heads, 16 sectors/track) is different from that in the partition table (30532 cylinders, 64 heads, 32 sectors/track)
Is this a problem? Can my file system be corrupted in the future because of this?

The "start: (c,h,s) expected (0,2,1) found (1,0,1)" warning in sfdisk is (as i found in some articles) caused by the partitions not ending on a cylinder boundary. This could be avoided if i have checked the "round to cylinders" option in gparted.
It seams however that this is harmless and there is no risk for the file system integrity.

Using "fdisk" i get no warnings at all:

Code:

fdisk -l

Disk /dev/mmcblk0: 32.0 GB, 32015122432 bytes
64 heads, 32 sectors/track, 30532 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x0000c26a

        Device Boot      Start         End      Blocks   Id  System
/dev/mmcblk0p1               1       21504    22020064    c  W95 FAT32 (LBA)
/dev/mmcblk0p2           21505       25600     4194304   83  Linux
/dev/mmcblk0p3           25601       26368      786432   82  Linux swap / Solaris
/dev/mmcblk0p4           26369       30464     4194304   83  Linux

If fdisk reports no problems at all may i assume that the differences in sfdisk reported disk geometry don't matter?
Where does the kernel keep the disk geometry parameters?

Thanks for your comments

Last edited by sacal; 2010-12-17 at 12:10.

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