fdisk and lvs size differences
Let's say I have a 500GB logical volume:
# lvs | grep san2_data san2_data san1 -wi-a- 500.00G
fdisk will report a bigger number:
# fdisk -l /dev/san1/san2_data
Disk /dev/san1/san2_data: 536.8 GB, 536870912000 bytes
Now, if fdisk -l would report 100 GB for some partition/disk/volume, a volume of which size should I create with "lvcreate" when I want to copy data from that partition/disk/volume to a new logical volume?
I wouldn't like to waste several gigabytes of space (this would happen if I create a 100G volume with lvcreate), perhaps there is some magic formula?
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Tomasz Chmielewski http://wpkg.org
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Quoted 11 lines · Tomasz Chmielewski
Let's say I have a 500GB logical volume:
# lvs | grep san2_data san2_data san1 -wi-a- 500.00Gfdisk will report a bigger number:
# fdisk -l /dev/san1/san2_dataDisk
/dev/san1/san2_data: 536.8 GB, 536870912000 bytes
It's just units; the G in lvm's output signifies powers-of-two units, wheras the GB reported by fdisk is in powers-of-ten (SI units).
See the lvm man pages for a description of the units supported (lower case are SI, upper case are powers-of-two).
Strictly speaking, the powers-of-two versions should use the SI binary prefixes (MiB, GiB, etc.):
http://en.wikipedia.org/wiki/Binary_prefix
Regards,
Bryn.
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Quoted 14 lines · Bryn M. Reeves
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Hash: SHA1Quoted 10 lines · Tomasz Chmielewski
Let's say I have a 500GB logical volume:
# lvs | grep san2_data san2_data san1 -wi-a- 500.00Gfdisk will report a bigger number:
# fdisk -l /dev/san1/san2_data
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Quoted 1 line
Disk
/dev/san1/san2_data: 536.8 GB, 536870912000 bytesIt's just units; the G in lvm's output signifies powers-of-two units, wheras the GB reported by fdisk is in powers-of-ten (SI units).
See the lvm man pages for a description of the units supported (lower case are SI, upper case are powers-of-two).
What lvm manual exactly? I didn't find anything about upper/lower case units supported in "man lvcreate" or "man lvm". In fact, it didn't make a difference here whether I used "g" or "G".
Of course, I could calculate it manually, but I'd rather have it done automatically.
# lvcreate -L500g -n san2_data san1 Logical volume "san2_data" created
# fdisk -l /dev/san1/san2_data
Disk /dev/san1/san2_data: 536.8 GB, 536870912000 bytes
# lvcreate -L500G -n san2_data san1 Logical volume "san2_data" created
# fdisk -l /dev/san1/san2_data
Disk /dev/san1/san2_data: 536.8 GB, 536870912000 bytes
# lvm version LVM version: 2.02.07 (2006-07-17) Library version: 1.02.08 (2006-07-17) Driver version: 4.11.0
This is on Debian Etch.
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Tomasz Chmielewski http://wpkg.org
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Quoted 3 lines · Tomasz Chmielewski
What lvm manual exactly? I didn't find anything about upper/lower case units supported in "man lvcreate" or "man lvm". In fact, it didn't make a difference here whether I used "g" or "G".
You're right - I was mistaken about using upper/lower to switch between units in LVM2.
It doesn't change the fact that this is why you're seeing a difference between the output of fdisk & the lvm tools though. LVM2 reports the size using binary prefixes (powers-of-two) and fdisk uses the SI units.
Regards,
Bryn.
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