Using LVM, how can I tell which logical volume is near full?

Question

I am getting errors that my disk is nearly full, but i am using three logical volumes, and would need to know which i need to extend. I still have 50GB unassigned.

Up until now i always extend all logical volumes together, but now i wanted to really only extend the needed volume.

[EDIT: output from the asked commands]

11:58:27|nva@nvaws[~] > df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/md0               5766196   5094104    379180  94% /
none                   1800512       264   1800248   1% /dev
none                   1806624       768   1805856   1% /dev/shm
none                   1806624       112   1806512   1% /var/run
none                   1806624         0   1806624   0% /var/lock
/dev/mapper/nvaws-db   5160576   1971944   2926488  41% /var/lib/postgresql
/dev/mapper/nvaws-usr
                      19223252   4957612  13289156  28% /usr
/dev/mapper/nvaws-home
                      61929340  29253760  29534180  50% /home
11:58:32|nva@nvaws[~] > 
12:01:13|nva@nvaws[~] > sudo vgdisplay
  --- Volume group ---
  VG Name               nvaws
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  8
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               145.93 GiB
  PE Size               4.00 MiB
  Total PE              37359
  Alloc PE / Size       26880 / 105.00 GiB
  Free  PE / Size       10479 / 40.93 GiB
  VG UUID               BBudpK-uLAo-ttes-g2ll-8jyI-xh74-J7xN8n

12:01:35|nva@nvaws[~] > sudo lvdisplay
  --- Logical volume ---
  LV Name                /dev/nvaws/home
  VG Name                nvaws
  LV UUID                bB5jZc-1jeP-Eptl-WKzi-20C1-1FCB-2EWm3p
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                60.00 GiB
  Current LE             15360
  Segments               4
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:0

  --- Logical volume ---
  LV Name                /dev/nvaws/usr
  VG Name                nvaws
  LV UUID                5XtAi2-Vwqo-ieHj-NrG5-jNbk-cE5z-35aHyj
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                40.00 GiB
  Current LE             10240
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:1

  --- Logical volume ---
  LV Name                /dev/nvaws/db
  VG Name                nvaws
  LV UUID                ahxV6P-vpjY-aRAw-bhcZ-oPGZ-2y9x-zhjlp5
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                5.00 GiB
  Current LE             1280
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:2

12:01:50|nva@nvaws[~] > 
12:02:03|nva@nvaws[~] > sudo pvdisplay
  --- Physical volume ---
  PV Name               /dev/md1
  VG Name               nvaws
  PV Size               145.93 GiB / not usable 960.00 KiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              37359
  Free PE               10479
  Allocated PE          26880
  PV UUID               cTYM85-ad2e-60i4-Pze5-9GXO-T4PC-DR7g9r

12:02:06|nva@nvaws[~] > 

I hope you guys can make more of that than i can :)

One remark: i extended the home logical volume yesterday, and added 10GB. It seemed the most likely candidate. SO i guess that will show itself.

Solution

From the data you provided, the size of your logical volumes is as follows:

partition : size : filesystem size

/dev/nvaws/home : 60 : 60

/dev/nvaws/usr : 40 : 20

/dev/nvaws/db : 5: 5

this looks ok, although you can extend your /usr filesystem if you need, to fill the lv.

the area that is causing the errors is none of the logical volumes but your root partition, which is the / directory (raid device md0)

This is 5.7gb in size (see first line of output of df command), and is 94% full. The / partition contains kernel files for booting (in /boot), config files (in /etc) and various log files in /var.

You must extend this / partition or reduce the usage - You must either extend this partition, or run tools to discover if there is anything than can be safely removed. I would start with removing old kernel files no longer required since these can be rather large (use ubuntu tweak application to do this), and also check size of logfiles in /var by running du -ksh /var/*

You may have lots of package files lying around as a result of software centre downloads. Ubuntu tweak - package cleaner will also help with clearing the cache.

Comments

[Simon B]

have you tried using system-config-lvm graphical LVM manager? installable from software centre.

[nathanvda]

I had never heard of it. It does not seem to help me though. I can't see how the logical volumes are used (free space per volume). But i am using a raid as well, so in that case they advise not to use it.

[Zoredache]

I am a bit confused. Why can't you just run df and see which volume is nearly full?

[Simon B]

can you provide more information: it is unsure where the 50gb is unassigned and what is full - disk or partition or logvol: can you provide output of df , and run the following commands as root, pvdisplay; lvdisplay; vgdisplay. also clarify the raid situation - if software raid then provide output of cat /proc/mdstat

[XTL]

Volumes don't get full. Filesystems get full. Volume groups may also get full. LVM doesn't concern itself with filesystems, mostly. Use df to see filesystem usage and vgs to see vg usage.