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Re: [linux-lvm] LVM Missing Space



Michael,

You're being misled -- fdisk says 639977390080 bytes ... divide that by 1024 / 1024 / 1024 *IS* 596Gb.

Problem is the difference between Gb and Gb ... ;) Some people just divide by 1 billion to get Gb, but ... others divide by 2^30, (1024 * 1024 * 1024) to get Gb.

LVM uses 2^30 to equal 1Gb,
Fdisk uses 10^9 to equal 1Gb.

-- Mitch




Michael MacFadden wrote:
Hello,

I have been trying to setup LVM for the first time on an RAID 5 Array.
The problem I have is that the raid array has 640Gb of usable space, but
when I create the LVM Physical Volume and Volume group I wind up with
596Gb.  I don't know where 44 gigs went to.  I am on Debian with a
2.6.17 kernel.

When I do fdisk -l I get this:

 fdisk -l

Disk /dev/sda: 639.9 GB, 639977390080 bytes
255 heads, 63 sectors/track, 77806 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sda doesn't contain a valid partition table

Disk /dev/hda: 163.9 GB, 163928604672 bytes
255 heads, 63 sectors/track, 19929 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1       19740   158561518+  83  Linux
/dev/hda2           19741       19929     1518142+   5  Extended
/dev/hda5           19741       19929     1518111   82  Linux swap / Solaris


Here you can see /dev/sda is 639.9GB.

I then do:

 $ pvcreate /dev/sda
  Physical volume "/dev/sda" successfully created
$ pvdisplay /dev/sda
  --- NEW Physical volume ---
  PV Name               /dev/sda
  VG Name
  PV Size               596.03 GB
  Allocatable           NO
  PE Size (KByte)       0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               po9rKd-gOKR-jfmx-yjUm-R5Wl-us2j-s6qZN1

You see here I only get 596Gb.  Also if I run the lvmdiskscan utility I get:

lvmdiskscan
  /dev/ram0  [        8.00 MB]
  /dev/sda   [      596.03 GB] LVM physical volume
  /dev/ram1  [        8.00 MB]
  /dev/hda1  [      151.22 GB]
  /dev/ram2  [        8.00 MB]
  /dev/ram3  [        8.00 MB]
  /dev/ram4  [        8.00 MB]
  /dev/ram5  [        8.00 MB]
  /dev/hda5  [        1.45 GB]
  /dev/ram6  [        8.00 MB]
  /dev/ram7  [        8.00 MB]
  /dev/ram8  [        8.00 MB]
  /dev/ram9  [        8.00 MB]
  /dev/ram10 [        8.00 MB]
  /dev/ram11 [        8.00 MB]
  /dev/ram12 [        8.00 MB]
  /dev/ram13 [        8.00 MB]
  /dev/ram14 [        8.00 MB]
  /dev/ram15 [        8.00 MB]
  0 disks
  18 partitions
  1 LVM physical volume whole disk
  0 LVM physical volumes


Again listing 596.03Gb.  What's going on here.  Why do I seem to be
getting less capacity in the physical volume than actually on the drive.
I really would like to use LVM but if I am going to lose 40Gigs then its
not really worth it.  Any help or ideas would be appreciated.

Regards,
Michael MacFadden

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