[linux-lvm] LVM Missing Space
Mitch Miller
mitch at mdmiller.com
Thu Sep 21 03:57:59 UTC 2006
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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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
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