Partition X does not end on cylinder boundary

While reviewing the partion layout on one of my hard drives, I noticed a number of “Partition X does not end on cylinder boundary” messages in the fdisk output:

$ fdisk /dev/sda
Command (m for help): p
Disk /dev/sda: 80.0 GB, 80000000000 bytes
255 heads, 63 sectors/track, 9726 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xac42ac42
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26         287     2097152   83  Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3             287        9726    75822111+  8e  Linux LVM

This was a bit disconcerting at first, but after a few minutes of thinking it dawned on me that modern systems use LBA (Logical Block Addressing) instead of CHS (Cylinder/Head/Sector) to address disk drives. If we view the partition table using sectors instead of cylinders:

$ sfdisk -uS -l /dev/sda
Disk /dev/sda: 9726 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0
   Device Boot    Start       End   #sectors  Id  System
/dev/sda1   *        63    409662     409600  83  Linux
/dev/sda2        409663   4603966    4194304  83  Linux
/dev/sda3       4603967 156248189  151644223  8e  Linux LVM
/dev/sda4             0         -          0   0  Empty

We can see that we end at a specific sector number, and start the next partition at that number plus one. I must say that I have grown quite fond of sfdisk and parted, and they sure make digging through DOS and GPT labels super easy.


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