Arch Linux

Shark

Member

From: /dev/zero

Registered: 2011-02-28

Posts: 686

Warning message: extended partition does not start at a cylinder bound

Hi

I have ran:

sudo sfdisk -l /dev/sda 

and this was the output:

 Disk /dev/sda: 38913 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1   *      0+   6353-   6354-  51031008+  83  Linux
/dev/sda2       6353+  18199-  11847-  95153152   83  Linux
/dev/sda3      18199+  38005   19807- 159099003   83  Linux
/dev/sda4      38006+  38913-    908-   7286784    5  Extended
/dev/sda5      38006+  38913-    908-   7285760   82  Linux swap / Solaris

This message really scared me:

Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.

First partion is Arch ofcourse, second is home partitition, the third personal data partition and the last is swap as you can see.

I was googling around but didn't get satisfied explanation if i shall repartition the disk. For info - Arch is working just fine, no problems but it bothers me anyway

---

If you have built castles in the air, your work need not be lost; that is where they should be. Now put foundations under them.
Henry David Thoreau

Registered Linux User: #559057

kachelaqa

Member

Registered: 2010-09-26

Posts: 216

Re: Warning message: extended partition does not start at a cylinder bound

This message really scared me:

Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.

since your partitions are all linux, the warnings don't really matter.

also note that a more accurate way to check where the partitions begin and end is like this:

sudo sfdisk -uS -l /dev/sda

this views things in terms of sectors, which i think is more realistic for large disks using logical block addressing.

Shark

Member

From: /dev/zero

Registered: 2011-02-28

Posts: 686

Re: Warning message: extended partition does not start at a cylinder bound

I ran:

sudo sfdisk -uS -l /dev/sda

Output:

Disk /dev/sda: 38913 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sda1   *        63 102062079  102062017  83  Linux
/dev/sda2     102062080 292368383  190306304  83  Linux
/dev/sda3     292368384 610566389  318198006  83  Linux
/dev/sda4     610568192 625141759   14573568   5  Extended
/dev/sda5     610570240 625141759   14571520  82  Linux swap / Solaris

---

If you have built castles in the air, your work need not be lost; that is where they should be. Now put foundations under them.
Henry David Thoreau

Registered Linux User: #559057

kachelaqa

Member

Registered: 2010-09-26

Posts: 216

Re: Warning message: extended partition does not start at a cylinder bound

I ran:

sudo sfdisk -uS -l /dev/sda

Output:

Disk /dev/sda: 38913 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sda1   *        63 102062079  102062017  83  Linux
/dev/sda2     102062080 292368383  190306304  83  Linux
/dev/sda3     292368384 610566389  318198006  83  Linux
/dev/sda4     610568192 625141759   14573568   5  Extended
/dev/sda5     610570240 625141759   14571520  82  Linux swap / Solaris

looking at the start and end sectors, you can now see that your four partitions (sda1, sda2, sda3 and sda5) do not overlap - so all is well.

the warning is only relevant if you had some old os (e.g. dos, windows nt) installed alongside arch which cares about cylinder boundaries.

gory details: http://tldp.org/HOWTO/Large-Disk-HOWTO-6.html

that warning is slightly annoying, though.

sfdisk has an -L option: "Do not complain about things irrelevant for Linux". so the warning *might* go away if you run:

sudo sfdisk -uS -L -l /dev/sda

Shark

Member

From: /dev/zero

Registered: 2011-02-28

Posts: 686

Re: Warning message: extended partition does not start at a cylinder bound

Thansk for info. The upper command still give me the same warning. Well everything is working and i am not planning to have DOS on  my laptop

---

If you have built castles in the air, your work need not be lost; that is where they should be. Now put foundations under them.
Henry David Thoreau

Registered Linux User: #559057