[linux-lvm] File system size difference betwen lvdisplay & df -h

[linux-lvm] File system size difference betwen lvdisplay & df -h

[Dayanand Math]

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Hi,

I am observing the file system size difference between df -h & lvdisplay
output for the systems with RHEL 4 (update 3 & 6).
Its showing the discrepancy in size between lvdisplay & df -h , If lvsize is
less than 1GB .. Is there any specific reason for that..

Regs,
DM

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Re: [linux-lvm] File system size difference betwen lvdisplay & df -h

[Bryn M. Reeves]

Dayanand Math wrote:
> Hi,
> 
> I am observing the file system size difference between df -h & 
> lvdisplay output for the systems with RHEL 4 (update 3 & 6). Its 
> showing the discrepancy in size between lvdisplay & df -h , If 
> lvsize is less than 1GB .. Is there any specific reason for that..
> 
> Regs, DM

You don't tell us what the discrepancy is or give an example, so it's
hard to make any useful suggestions.

Can you provide sample command output that shows the discrepancy you
are referring to?

Regards,
Bryn.

Re: [linux-lvm] File system size difference betwen lvdisplay & df -h

[Dayanand Math]

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Hi,

The following df -h & lvdisplay shows the discrpancy..What could be the
reson?
I am referring to the discrepancy between LV Size in lvdisplay &  total
size df -h output of the corresponding file system.

 df -h /test
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg00-lv_test
                      124M   11M  107M   9% /test

# lvdisplay -v /dev/vg00/lv_test
    Using logical volume(s) on command line
  --- Logical volume ---
  LV Name                /dev/vg00/lv_test
  VG Name                vg00
  LV UUID                t9RjGa-hKR3-AQmA-sLqD-4PaI-fkJ3-99c1dx
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                128.00 MB
  Current LE             4
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:3


# df -h /home
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg00-lv_home
                     1008M   37M  921M   4% /home

# lvdisplay -v /dev/vg00/lv_home
    Using logical volume(s) on command line
  --- Logical volume ---
  LV Name                /dev/vg00/lv_home
  VG Name                vg00
  LV UUID                1wlyyE-RFID-0Dbi-DES8-lrDk-GLlB-6wpEBZ
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.00 GB
  Current LE             32
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:1
Regs,
DM


On 2/17/09, Bryn M. Reeves <bmr@redhat.com> wrote:
>
> Dayanand Math wrote:
>
>> Hi,
>>
>> I am observing the file system size difference between df -h & lvdisplay
>> output for the systems with RHEL 4 (update 3 & 6). Its showing the
>> discrepancy in size between lvdisplay & df -h , If lvsize is less than 1GB
>> .. Is there any specific reason for that..
>>
>> Regs, DM
>>
>
> You don't tell us what the discrepancy is or give an example, so it's
> hard to make any useful suggestions.
>
> Can you provide sample command output that shows the discrepancy you
> are referring to?
>
> Regards,
> Bryn.
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>

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Re: [linux-lvm] File system size difference betwen lvdisplay & df -h

[Bryn M. Reeves]

Dayanand Math wrote:
> Hi,
> 
> The following df -h & lvdisplay shows the discrpancy..What could be
> the reson? I am referring to the discrepancy between LV Size in
> lvdisplay &  total size df -h output of the corresponding file
> system.

That just appears to be normal file system overheads. All file systems
use some of the total space available on a device for storing internal
structures and data (the file system's metadata). You'll see this with
any block device type, e.g. with a 64M USB key:

# df -h /mnt
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdc1              61M  5.3M   53M  10% /mnt

Regards,
Bryn.

Re: [linux-lvm] File system size difference betwen lvdisplay & df -h

[Lupe Christoph]

On Tuesday, 2009-02-17 at 16:35:53 +0530, Dayanand Math wrote:

> The following df -h & lvdisplay shows the discrpancy..What could be the
> reson?

Get a spelin cheker :-P

> I am referring to the discrepancy between LV Size in lvdisplay &  total
> size df -h output of the corresponding file system.

>  df -h /test
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/mapper/vg00-lv_test
>                       124M   11M  107M   9% /test

Please use df -k to get exact figures.

> # lvdisplay -v /dev/vg00/lv_test
>   LV Size                128.00 MB

Depending on the filesystem type, which we don't know, the filesystem
may not use all available space because of its structure, i.e. because
you don't get an integral number of cylinder groups out of the available
space. This is less obvious with large (i.e. multi-Gigabyte)
filesystems.

Please do not top-post and remove all fluff in your answers.

> On 2/17/09, Bryn M. Reeves <bmr@redhat.com> wrote:

> > Dayanand Math wrote:

HTH,
Lupe Christoph
-- 
| There is no substitute for bad design except worse design.                   |
| /me                                                                          |