Task - problem.
I make universal extender of filesystem (for example extend fs in
virtual computer after resize disk or add space to filesystem in hosting
server, etc.). Before extend volume group and filesystem I want to make
plan of extends. For plan I need to know how many bytes it can add to VG
from disk/partition. I know size of disk, partition, free space - and I
have to know free space after create PV on free space of disk.
I don't know how many LV will be on target system (system, which run
fsextender), I don't know fragmentation of it and etc.
Is any way to know how many space take metadata and how many space will
be usable?
On 01.10.2015 14:26, Zdenek Kabelac wrote:
Dne 30.9.2015 v 17:28 Timofey Koolin napsal(a):
Task: calc usable space of PV before create PV and before create
partition for
PV.
In my experiments usable space in PV = PVSize / ExtentSize *
ExtentSize with
integer operations.
But when Metadata may be large - when LVM have a lot of logical
volumes and it
can take more space.
I found in /etc/lvm/lvm.conf parameter pvmetadatasize = 255 secotors
(default).
What will if metadata will grow to more then 255 sectors?
If you plan to host lots of LVs within a single VG (in range of hundreds)
use i.e. 'pvcreate --metadatasize 5M'
(i.e. ~7000 linear single segment LVs takes around 2.2MB and you need
space for at least 2 metadatas to fit in)
What I'm not quite sure is your 'task' - what's the purpose ?
Do you want to do some 'sector' precise emulation of what lvm2 is
doing by watching resuls of couple command with just subset of it's
options ?
Isn't better to read man pages ?
Zdenek
_______________________________________________
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/
--
Timofey Koolin
_______________________________________________
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/