On 7/12/18 10:15 am, G C wrote:
Not really clear to me but no we're not using an SSD.
(I'm not an expert on LVM so bear with me)
Are you saying that I would add some of the new PV to the existing LV
so it can be utilized and then perform a pvmove later?
If I'm using part of the new PV as part of the LV how would I ensure
that it's not overwritten when performing the pvmove later?
Here are my scenarios below maybe you can add what you're thinking
into it and it will make more sense to me.
Original Scenario:
DISK_1 2TB
pvcreate /dev/sdd
vgcreate vg01 /dev/sdd
lvcreate -n 01lv -l 100%FREE vg01
Device: /dev/vg01/01lv
# drbd setup
drbdadm create-md clusterdb
drbdadm up clusterdb
drbdadm primary --force clusterdb
mkfs.ext4 /dev/drbd0
mkdir /01
mount /dev/drbd0 /01
RESIZE (ONLINE) - really slow currently takes over 20hours for the
migration, final outcome is that we have only one Physical disk after
the move
DISK_2 3TB
pvcreate /dev/sde
vgextend vg01 /dev/sde
pvmove /dev/sdd /dev/sde
vgreduce vg01 /dev/sdd
pvremove /dev/sdd
lvextend -l +100%FREE /dev/vg01/01lv
drbdadm -- --assume-clean resize clusterdb
resize2fs /dev/drbd0
For me, it is like this (simple case with SSD's)
pvcreate /dev/sde
vgextend vg01 /dev/sde
lvextend -L+900G /dev/vg01/01lv
drbdadm resize clusterdb
A somewhat simple solution to do what you want might be this (untested,
so check it on a VM or test env first):
pvcreate /dev/sde
vgextend vg01 /dev/sde
lvcreate -n temp -l <xxx> vg01
Note, the size xxx is exactly equal to the size of 01lv which you can
check with lvdisplay. This will allocate the first part of sde to a new
LV called temp, it is just here to use up the space.
lvextend -l+100%FREE /dev/vg01/01lv
Note, I don't usually use this 100%FREE method, but I assume it will
work right...
drbdadm resize clusterdb
This effectively means your LV 01lv is split across sdd and sde, which
might improve performance, but increases risk if either disk dies.
At any time, you can now lvremove /dev/vg01/temp and can then do your
pvmove which will move the first 2TB of 01lv from sdd to the beginning
of sde.
There is a more complicated method, but this is what I would do if faced
with your problem. I've also successfully used this script:
https://bisqwit.iki.fi/source/lvm2defrag.html
Which can assist you to ensure that the entire disk ends up contiguous
(though you would need to have at least some temporary space, so better
not to allocate 100% of the space in the step after you create the temp LV).
Also, why do you allocate 100% of the space? Why not leave some space
for snapshots, or for future growth? If you had left 100G spare, then
right now you would simply lvextend to use up the last 100G, and then
have some time to deal with arranging the upgrade. Just my suggestions,
but I don't understand your needs.
Regards,
Adam
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