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I want to check used space for each and every partition in Linux. I am using this command to get size of each partition but not able to get used space or free space.

$ cat /proc/partitions
major minor   #blocks  name

   8      0   16777216  sda
   8      1     512000 sda1
   8      2   16264192 sda2
 253      0   14585856 dm-0     
 253      1    1675264 dm-1

I am able to get used space using df command, but it shows filesystems and it's not able to get used space for all the partitions like /dev/sda2.

$ df -Tl
Filesystem           Type  1K-blocks    Used Available Use% Mounted on
/dev/mapper/VolGroup-lv_root
                     ext4   14225776 3791704   9704780  29% /
tmpfs                tmpfs    961596      72    961524   1% /dev/shm
/dev/sda1            ext4     487652   40187    421865   9% /boot

I want to calculate disk utilization. Is there any way to get used space and total space for each and every partition?

Kamil Maciorowski
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Free Aac
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  • What's wrong with df exactly? Do you want to see the results for filesystems that are not mounted? Or do you have a filesystem that spawns over multiple devices and you want to check used space for each of them separately (whatever it means)? Or what? – Kamil Maciorowski Sep 04 '17 at 07:00
  • actually i want to calculate disk utilization using used space and available space for each partition in linux. using cat /proc/partitions it is showing all partitions with size but when i use df -h it is not showing /dev/sda2 partition with used space. – Free Aac Sep 04 '17 at 07:07
  • Is it mounted? Is there a filesystem there in the first place? In general it may be a swap partition, unsupported filesystem or whatever. I guess there's no tool that covers all the "whatevers". – Kamil Maciorowski Sep 04 '17 at 07:13
  • is there any chat facility to discuss with you? – Free Aac Sep 04 '17 at 07:16
  • I could start a chat room, I guess, but it's not how this site works. You should state your specific problem to the entire community. What is your aim? What is /dev/sda2? Avoid XY problem and improve your question maybe (you may [edit] to add new details). – Kamil Maciorowski Sep 04 '17 at 07:21
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    There is no notion of "used space" in a partition, because the partition concept doesn't know the files that are put in it (or you can consider that the partition is 100% full since all of it is allocated to a file system). The used space is only pertinent for a file system, because it can compare the size allocated to it (the partition size) and the space used by the files currently on it. – xenoid Sep 04 '17 at 08:04
  • Your question is still not clear. What exactly is wrong with "df -h"? Formatting your question would help. – Ramhound Sep 04 '17 at 08:06
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    I think your /dev/sda2 is used by LVM to host dm-0 etc. In this context it's 0% free, i.e. you cannot write to it without messing LVM. However you can write to /dev/mapper/VolGroup-lv_root mounted under / and this data will be stored on /dev/sda2 somehow. That's my guess. – Kamil Maciorowski Sep 04 '17 at 08:09
  • @xenoid, i got it then how to calculate the disk utilization because for sda2 not able to get used space using "df"any idea. actually i am new to this linux – Free Aac Sep 04 '17 at 08:59
  • @KamilMaciorowski yes kamil, /dev/sda2 is under LVM

    pvs

    PV VG Fmt Attr PSize PFree

    /dev/sda2 VolGroup lvm2 a--u 15.51g 0

    so how can i take used space for /dev/sda2? currently i am taking total space as sda and used space as sda1+sda2. so disk utilization as (sda1+sda2/sda)*100 and i am getting 99.9%.

     – Free Aac Sep 04 '17 at 09:02

1 Answers1

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Since df -Tl shows a volumegroup it means you are using LVM on top of normal partitioning. This means that for the operating system the partition is always fully utilized and will show no free space. With df you can see the free space in the logical volume root. If you want to see more info from lvm you can run for example pvdisplay to see how the physical volumes are configured, and then lvdisplay to see how the logical volumes are configured.

Elias
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  • if LVM is configured then how to calculate this disk usage?. – Free Aac Sep 05 '17 at 07:49
  • If you really just want to know how much space is left, just use df -h . The lvm volume shows just as a normal disk, you just manage it differently as you can grow the volume by adding disks or partitions to it. – Elias Sep 05 '17 at 10:17
  • In Aix by doing lspv hdisk0 able to get total PPs, Used PPs.. and able to calculate disk utilization, but in linux not able to understand pvdisplay, I tried pvdisplay /dev/sda2 i am getting [code]PV Size 15.51 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 3970 Free PE 0 Allocated PE 3970[/code] How to calculate Disk utilization by using this in linux? – Free Aac Sep 05 '17 at 12:03
  • pvdisplay would show free PE only if you have not allocated the space from a pv to an lv. So a logical volume is the layer on top of the physical volumes. And a logical volume shows directly as a mount point. So if you need to know how much of each partition is allocated to a pv, pvdisplay shows that, but normally that is 100%. df then shows the total available space in the whole logical volume and doesn't care about the partitions since they are not directly mounted to the OS. – Elias Sep 06 '17 at 10:53