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Re: [linux-lvm] calculating free capacity from pvdisplay and lvdisplay



B. Thus the total full space would come to 4.89 TB. But the sum of full
space of all my LV's is only around 3 TB (based on the output of df)

It's the same thing as making a new partition covering your whole drive,
then wondering why fdisk says you can't make another partition.  Just
because you haven't stored files in that partition, it's still takes
up the whole drive.

df shows that your LVs take up 8.6TB: 6TB + 600 GB + 2 TB.
Therefore, you are using 8.6TB of disk space for those LVs.
Some of the space WITHIN each LV might not be used for files,
but it has been dedicated to that LV.

df also shows that the filesystems on the LVs have free space for
more files.  So you can put more files on those LVs, which is a
different thing than having space to make more LVs.

I'm not good at explaining things, so sometimes I try explaining three
different ways.  I have six cereal boxes, each half empty.  I put the
boxes in a bag.  The bag is now full.  The cereal boxes may not be full,
but they fill up the bag.  The cereal boxes are your half empty LVs and
the bag is your drives.

Layers:

hard drive
partition (can be skipped)
physical volume
volume group
logical volume
file system
--
Ray Morris
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On 08/10/2010 09:25:15 PM, Rahul Nabar wrote:
Some of the physical volumes show "Allocatable           yes (but
full)" while others don't. How does one relate this to the actual
capacity? THe reason I am confused is that 3 of my PV's show up as
full and each is 1.63 TB. Thus the total full space would come to 4.89
TB. But the sum of full space of all my LV's is only around 3 TB
(based on the output of df)

I've reproduced the outputs of pvdisplay, lvdisplay and df below.

I'm confused! Any pointers?

--
Rahul


[root eustorage ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sdb
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               0
  Allocated PE          428351
  PV UUID               wDdbmP-2n5m-98HD-Ewqk-Q3y0-lnMf-rsaVXt

  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               0
  Allocated PE          428351
  PV UUID               75i75q-2rec-2FMf-eyPa-W0nF-zFHH-PIAvvc

  --- Physical volume ---
  PV Name               /dev/sdd
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               0
  Allocated PE          428351
  PV UUID               vo2Jh2-PfFC-eOj4-GYnP-Jx1I-Sisu-2nY4lC

  --- Physical volume ---
  PV Name               /dev/sde
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               38140
  Allocated PE          390211
  PV UUID               EK7cvF-IZjf-PJVw-d2RR-lCdt-kOSD-iqFtOf

  --- Physical volume ---
  PV Name               /dev/sdf
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               140607
  Allocated PE          287744
  PV UUID               fQXN8S-HhYu-weoq-kbuz-BrxZ-6WQk-6ydBDw

  --- Physical volume ---
  PV Name               /dev/sdg
  VG Name               euclid_highperf_storage
  PV Size               1.63 TB / not usable 4.00 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              428351
  Free PE               140607
  Allocated PE          287744
  PV UUID               i7GD1d-rbd2-efKd-uK3u-D3S2-BxJv-UkrNve

[root eustorage ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              76G  8.6G   64G  12% /
/dev/sda6              19G  365M   17G   3% /var
/dev/sda5              15G  165M   14G   2% /tmp
/dev/sda1             487M   17M  445M   4% /boot
tmpfs                  24G     0   24G   0% /dev/shm
/dev/mapper/euclid_highperf_storage-LV_home
                      6.0T  1.4T  4.4T  24% /home
/dev/mapper/euclid_highperf_storage-LV_export
                      591G   17G  550G   3% /opt
/dev/mapper/euclid_highperf_storage-LV_polhome
                      2.0T  1.5T  386G  80% /polhome
[root eustorage ~]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/euclid_highperf_storage/LV_home
  VG Name                euclid_highperf_storage
  LV UUID                gu7yo1-TYYr-ucHG-QSDk-y8HD-ETrs-Z5kCk9
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                6.00 TB
  Current LE             1572864
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     1536
  Block device           253:0

  --- Logical volume ---
  LV Name                /dev/euclid_highperf_storage/LV_export
  VG Name                euclid_highperf_storage
  LV UUID                1lktLy-Hgn3-qS1m-41VJ-5kNY-DMyb-1ri4Th
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                600.00 GB
  Current LE             153600
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     1536
  Block device           253:1

  --- Logical volume ---
  LV Name                /dev/euclid_highperf_storage/LV_polhome
  VG Name                euclid_highperf_storage
  LV UUID                xqpOX5-HFey-H0qi-NgjP-NVS7-FwDb-zbiK8m
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                2.00 TB
  Current LE             524288
  Segments               4
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

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