==== Required information ====
- iRedMail version (check /etc/iredmail-release): .9.2
- Linux/BSD distribution name and version: Re Hat 7.3
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):Apache
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- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I'm running out of room on my centos root volume. So I need to either add a drive and use LVM to add more space to a volume? OR down size the home centos volume by 100g then add that to the root centos volume.

Here is my drive layout I need more room on the root centos volume.
[root@mail # pvs
  PV         VG     Fmt  Attr PSize   PFree
  /dev/sda2  centos lvm2 a--  931.02g 64.00m

[root@mail # vgs
  VG     #PV #LV #SN Attr   VSize   VFree
  centos   1   3   0 wz--n- 931.02g 64.00m

[root@mail # lvs
  LV   VG    Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Con    vert
  home centos -wi-ao---- 873.21g
  root centos -wi-ao----  50.00g
  swap centos -wi-ao----   7.75g

So my questions are ...??
Do I need to boot off CD or something to do this LVM or can I just do it online?
I understand I need to shut it down to add a new hard drive, but can I resize the Volume while mounted?

Thanks for any help on this!!!