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Linux fdisk

Posted on 2014-02-27
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Last Modified: 2014-03-14
in the screenshot below regarding fdisk command, I see dev/sda and dev/sdb , I also see dev/sda1 and dev/sda2.

I wonder if someone can explain the meaning of the display.

Thank you

fdisk
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Question by:jskfan
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13 Comments
 
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by:farzanj
farzanj earned 167 total points
ID: 39892301
/dev/sda  is one device  -- like a drive
/dev/sda1 or /dev/sda2 refer to the partitions on that device

It cannot read the partition table of /dev/sdb device.  It may not be partitioned or partitioned in a non -Linux system, empty, etc.

Also /dev/sda1 is the boot partition.  /dev/sda2 is used by LVM
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by:Dave Gould
Dave Gould earned 166 total points
ID: 39892338
sda is a physical disk of 1044 cylinders. It has been partitioned into 2 partitions.
sda1 is a partition from cylinder 1 to 13
sda2 is a partition from 14 to the end

the id 83 means that it is a linux system disk and 8e means that it is used for LVM (volume manager)

sdb is another physical disk of 261 cylinders but it has not been partitioned or the linux machine cannot recognize the disk type
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Author Comment

by:jskfan
ID: 39892394
what do they mean by Linux LVM, I have seen ext3,ext4,LVM…
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Author Comment

by:jskfan
ID: 39892405
in Ubuntu I see Linux and solaris...
ubuntu
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by:farzanj
farzanj earned 167 total points
ID: 39892423
LVM means logical volumes.  It is a way to keep very flexible partitions.  You can change their size very easily and a logical volume can span multiple devices as well.

Ubuntu is showing Linux swap, which is a supplementary area for RAM.

You can google these concepts.

ext3 and ext4 are Linux file systems, like in Window we have FAT and NTFS, etc.
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by:jskfan
ID: 39892609
Thank you…
so Linux has the following partitions:
LVM it sounds  like RAID
Ext3 ,Ext4
Linux
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by:Sandy
Sandy earned 83 total points
ID: 39892802
Partitions are something which are usually not resized, Volume are somthing which can be re-sized..

which fdisk you created partitions then with LVM and RAID you create volumes and metadevices.

on these partitions/volumes/metadevices you create filesystem by formatting these raw block device with ext2/3/4 swap etc....

TY/SA
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Author Comment

by:jskfan
ID: 39893629
Any link that explains disk partitions and the commands related to disks and volumes…?

Fdisk and Fd are already confusing to me, there might be more other commands that pitch in and are used in Disk world of linux
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by:Dave Gould
Dave Gould earned 166 total points
ID: 39894010
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Expert Comment

by:Sandy
ID: 39894014
Try the links trappa01 gien :)

TY/SA
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Expert Comment

by:Dave Gould
ID: 39894046
gien ?
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Accepted Solution

by:
skullnobrains earned 84 total points
ID: 39896951
Thank you…
so Linux has the following partitions:
LVM it sounds  like RAID
Ext3 ,Ext4
Linux

no
a disk contains volumes that are shown in fdisk. volume types include
linux swap
linux
LVM (which will host other volumes, yes it can do raid)
...

note that the same volumes will be visible in any OS with similar information (obviously LVM volumes will need LVM to be available on your OS)

on a volume, you can install filesystems such as
ext2
ext3
ext4
reiserfs
xfs
...


in Ubuntu I see Linux and solaris...

not really. partition types have been assigned ids a long time ago.
there happens to be a conflict between the number used by old solaris installs and linux swap

you'll find the list of registered partition types easily by googling for "partiton types"

note that installing a fat filesystem in a partition with a solaris type will work. the information is only declarative and such settings might only confuse some boot loaders. you don't even have to partition a disk at all : it is perfectly workable to directly install a filesystem on a physical disk with no partition layer

--

note that all of this information is not linux-specific in any way. this is just the way pc computers and derivatives work.
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Author Closing Comment

by:jskfan
ID: 39930072
Thank you Guys!
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