How to partition a drive using fdisk
fdisk is the Linux disk partitioning utility. It should only be ran on unmounted drives, so a Live CD or similar is advised.
To use fdisk, you must be root
su
In this instance, I am running off a CentOS 6.4 Live CD, with a populated 1.5TB drive (/sdb) with many partitions and a brand new 2.0TB drive (sda) that I indend to format similarly.
You can see what drives are available by looking in the /dev/ folder
ls -l /dev/sd* brw-rw----. 1 root disk 8, 0 Oct 16 01:30 /dev/sda brw-rw----. 1 root disk 8, 16 Oct 16 01:30 /dev/sdb brw-rw----. 1 root disk 8, 17 Oct 16 01:30 /dev/sdb1 brw-rw----. 1 root disk 8, 18 Oct 16 01:30 /dev/sdb2 brw-rw----. 1 root disk 8, 19 Oct 16 01:30 /dev/sdb3 brw-rw----. 1 root disk 8, 20 Oct 16 01:30 /dev/sdb4 brw-rw----. 1 root disk 8, 21 Oct 16 01:30 /dev/sdb5 brw-rw----. 1 root disk 8, 22 Oct 16 01:30 /dev/sdb6
You can plainly see that /sda is the new drive, since it contains no partitions.
Current partitioning rules say you can only have 4 primary partitions. If you need more than 4, you will have to create one partition as an extended partition, which can then be subdivided into several logical partitions. This should become clear shortly.
The Plan
Understanding how you will use your drive now will eliminate a lot of headaches down the road. For this application, I’m going to create 3 Primary Partitions plus 1 extended, in which I will put a couple of logical partitions.
Run fdisk
fdisk /dev/sdb
blah blah blah Command (m for help):
To view the current partitions and disk information, use for Print
Command (m for help): p
Disk sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x4f67c248
Device Boot Start End Blocks Id System
Command (m for help):
Create Primary Partitions
To create a new partition, type ‘n’
Command (m for help): n
Command action
e extended
p primary partition (1-4)
Since this will be a primary partition, press ‘p’, then ‘1’ for the first partition.
Command action e extended p primary partition (1-4) p Partition number (1-4): 1
Now we need to determine the start cylinder and size of the partition. Since this is the first, use the default of ‘1’ by pressing
First cylinder (1-243201, default 1):
Using default value 1
Finally we determine the size. I’m going to make this 250G, so I’ll enter “+250G” and let the program determine my last cylinder for me
Last cylinder, +cylinders or +size{K,M,G} (1-243201, default 243201): +250G
Command (m for help):
That’s it for the first partition! Here are the entries for creating the second and 3rd, which will both be 250G as well.
Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 2 First cylinder (32636-243201, default 32636): Using default value 32636 Last cylinder, +cylinders or +size{K,M,G} (32636-243201, default 243201): +250G Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 3 First cylinder (65272-243201, default 65272): Using default value 65272 Last cylinder, +cylinders or +size{K,M,G} (65272-243201, default 243201): +250G
Lets take a peek at what our drive should look like at this point by getting a current printout:
Command (m for help): p
Disk sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x4f67c248
Device Boot Start End Blocks Id System
sda1 1 32636 262148636+ 83 Linux
Partition 1 does not start on physical sector boundary.
sda2 32636 65272 262140640 83 Linux
sda3 65272 97907 262148668 83 Linux
Command (m for help):
Create an Extended Partition
In order to create more than 1 more partition (we will create a Linux Swap partition, a data partition and leave some room for additional partitions at a later date), we will create an extended partition with the remaining space and then subdivide that into the remaining partitions.
This process is the same as the previous, except this time we will select for the type and to use the remaining available space, we just need to use the default for both the first and last cylinders.
Command (m for help): n Command action e extended p primary partition (1-4) e Selected partition 4 First cylinder (97907-243201, default 97907): Using default value 97907 Last cylinder, +cylinders or +size{K,M,G} (97907-243201, default 243201): Using default value 243201 Command (m for help):
Create Logical Partitions
Okay, we are finally ready to create our logical partitions. This time, the program knows we are out of partitions, so we can only create logical paritions out of the extended that we just created, so you will NOT be asked if this is primary or extended, or for a partition number!
Our swap partition will be 20G.
Command (m for help): n First cylinder (97908-243201, default 97908): Using default value 97908 Last cylinder, +cylinders or +size{K,M,G} (97908-243201, default 243201): +20G Command (m for help):
Our data partition will be 1TB (1000G)
Command (m for help): n First cylinder (100520-243201, default 100520): Using default value 100520 Last cylinder, +cylinders or +size{K,M,G} (100520-243201, default 243201): +1000G Command (m for help):
Lets take another look at where we stand:
Command (m for help): p
Disk sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x4f67c248
Device Boot Start End Blocks Id System
sda1 1 32636 262148636+ 83 Linux
Partition 1 does not start on physical sector boundary.
sda2 32636 65272 262140640 83 Linux
sda3 65272 97907 262148668 83 Linux
sda4 97907 243201 1167074056+ 5 Extended
sda5 97908 100520 20980860+ 83 Linux
Partition 5 does not start on physical sector boundary.
sda6 100520 231063 1048586616+ 83 Linux
Partition 6 does not start on physical sector boundary.
Command (m for help):
Believe it or not, there are only a few steps remaining.
Setting the Swap Partition Type
You’ll notice in the last step, all partitions (except 4) are created as type 83, or Linux partitions. Our swap partition (Partition 5) needs to be set as a ‘Swap’.
The command to set the partition type is
In the section below, I’ve opted to ist the available type codes. The type code for a swap partition is ’82’.
Command (m for help): t Partition number (1-6): 5 Hex code (type L to list codes): L 0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris 1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT- 2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT- 3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT- 4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx 5 Extended 42 SFS 86 NTFS volume set da Non-FS data 6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / . 7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility 8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt 9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/ 10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b 11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor 12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor 14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary 16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS 17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE 18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto 1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep 1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT 1e Hidden W95 FAT1 Hex code (type L to list codes): 82 Changed system type of partition 5 to 82 (Linux swap / Solaris) Command (m for help):
Setting the Boot Flag
To allow a partition to function as a bootable OS, the boot flag needs to be set. We’ll set this on partitions 1, 2 and 3.
Command (m for help): a Partition number (1-6): 1 Command (m for help): a Partition number (1-6): 2 Command (m for help): a Partition number (1-6): 3 Command (m for help): p Disk sda: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x4f67c248 Device Boot Start End Blocks Id System sda1 * 1 32636 262148636+ 83 Linux Partition 1 does not start on physical sector boundary. sda2 * 32636 65272 262140640 83 Linux sda3 * 65272 97907 262148668 83 Linux sda4 97907 243201 1167074056+ 5 Extended sda5 97908 100520 20980860+ 82 Linux swap / Solaris Partition 5 does not start on physical sector boundary. sda6 100520 231063 1048586616+ 83 Linux Partition 6 does not start on physical sector boundary.
Save and Exit
Until now, all settings are in memory only and NO changes have been made to the drive. To set these changes in stone, (from which there is no turning back), simply press .
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
Verify Changes
Remember how we checked the available drives and partitions at the start of this tutorial? Let’s run that command again and you’ll now see the new partitions on /sda
ls -l /dev/sd*
brw-rw----. 1 root disk 8, 0 Oct 16 04:12 /dev/sda brw-rw----. 1 root disk 8, 1 Oct 16 04:12 /dev/sda1 brw-rw----. 1 root disk 8, 2 Oct 16 04:12 /dev/sda2 brw-rw----. 1 root disk 8, 3 Oct 16 04:12 /dev/sda3 brw-rw----. 1 root disk 8, 4 Oct 16 04:12 /dev/sda4 brw-rw----. 1 root disk 8, 5 Oct 16 04:12 /dev/sda5 brw-rw----. 1 root disk 8, 6 Oct 16 04:12 /dev/sda6 brw-rw----. 1 root disk 8, 16 Oct 16 01:30 /dev/sdb brw-rw----. 1 root disk 8, 17 Oct 16 01:30 /dev/sdb1 brw-rw----. 1 root disk 8, 18 Oct 16 01:30 /dev/sdb2 brw-rw----. 1 root disk 8, 19 Oct 16 01:30 /dev/sdb3 brw-rw----. 1 root disk 8, 20 Oct 16 01:30 /dev/sdb4 brw-rw----. 1 root disk 8, 21 Oct 16 01:30 /dev/sdb5 brw-rw----. 1 root disk 8, 22 Oct 16 01:30 /dev/sdb6
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