On Fri, Apr 5, 2019 at 4:36 AM Aleksei Gutikov <aleksey.gutikov@xxxxxxxxxx> wrote: > > Hi all, > > It seems a little-bit weird, > while we can format disk with ceph-osd --mkfs, > and then read labels with ceph-bluestore-tool show-labels. > > So is it required to use LVM? It isn't a requirement. > Or it gives any advantages that we do not see from our point? It does! Lets assume that you've manually formatted a disk with ceph-osd. How do you start the OSD? Something had to create the SystemD unit. If you start the OSD manually, what happens when you reboot the system? This is not an LVM thing, but worth mentioning still! The way we do things with LVM, allows you to reboot a system while ceph-volume picks up the devices when they become available, being able to tell what devices belong to what OSD. There are many advantages for using LVM, we initially chose it because it made the device discovery portion a breeze (unlike dealing with partitions) and we were able to store OSD metadata in LVM itself. If you are manually partitioning a disk and creating the OSD with some ad-hoc tools, or using the no-longer-available ceph-disk, you can tell ceph-volume to inspect the running OSD and create a systemd unit that will ensure that OSD starts up with every device mounted (and decrypted if needed). In short, there is no requriement, you can do things manually, it is still worth using ceph-volume to help set up the devices for the OSD. But the recommended way is with LVM. > > > -- > > Best regards, > Aleksei Gutikov > Software Engineer | synesis.ru | Minsk. BY
