no Linstor required
tested on ubuntu and slackware current (oct 2021)
dual-primary are only required temporarily during XEN migration. but we have to enable it: with it disabled, the replicated vdisk does not come up as primary by itself, and remains in secondary state unless manually told to.
DRBD v8 does not seem to support the diskless feature hence we go for v9.
make sure the nodes communicate by short hostnames and also validate SSH fingerprints — this is at least required to synchronize the confs across the farm through rsync or scp.
vi /etc/hosts 192.168.122.11 slack1.localdomain slack1 192.168.122.12 slack2.localdomain slack2 192.168.122.13 slack3.localdomain slack3 ssh slack1 ssh slack2 ssh slack3 ssh-keygen -t ed25519 cat .ssh/id_ed25519.pub vi .ssh/authorized_keys
pick an install method
and load the v9 modules
modprobe drbd lsmod | grep drbd modinfo drbd cat /proc/drbd
and also install thin tools and tune LVM2
the design we’re attempting to PoC as a MWE here is as such:
/data/ as GFS2, OCFS2 or NFS for XEN guest configs /dev/thin/GUEST-NAME logical volumes for XEN guest file-systems mirrors
assuming a single additional block device for both the shared file-system and LVM2 thin provisioning to live on
fdisk /dev/vdb partition 1 -- 10G for xen configs partition 2 -- all the rest for LVM2
we don’t need CLVM nor lvmlockd/sanlock/dlm because
all nodes
pvcreate /dev/vdb2
vgcreate thin /dev/vdb2
create a specific LV as a thin pool. this sometimes gets stuck — this is why we rebooted the machine once lvm2 and thin tools got installed
lvcreate --extents 100%FREE --thin thin/pool
you can now proceed with the casual LVs within the thin pool
node1 and node2
lvcreate --virtualsize 10G --thin -n slack thin/pool
ls -lF /dev/thin/slack
slack1
the global config
mv -i /etc/drbd.conf /etc/drbd.conf.dist
mv /etc/drbd.d/ /etc/drbd.d.dist/
mkdir /etc/drbd.d/
vi /etc/drbd.conf # new file
global {
usage-count yes;
udev-always-use-vnr;
}
common {
net {
protocol C;
# v9
fencing resource-only;
#fencing resource-and-stonith;
allow-two-primaries yes;
}
options {
quorum majority;
#quorum-minimum-redundancy 2;
on-no-quorum io-error;
}
handlers {
quorum-lost "echo b > /proc/sysrq-trigger";
}
disk {
read-balancing when-congested-remote;
}
}
include "drbd.d/*.res";
now some resource
vi /etc/drbd.d/slack.res
resource slack {
device /dev/drbd1;
meta-disk internal;
on slack1 {
# v9
node-id 1;
address 192.168.122.11:7701;
disk /dev/thin/slack;
}
on slack2 {
node-id 2;
address 192.168.122.12:7701;
disk /dev/thin/slack;
}
on slack3 {
node-id 3;
address 192.168.122.13:7701;
disk none;
}
# v9
connection-mesh {
hosts slack1 slack2 slack3;
}
}
scp /etc/hosts slack2:/etc/
scp /etc/hosts slack3:/etc/
scp /etc/drbd.conf slack2:/etc/
scp /etc/drbd.conf slack3:/etc/
scp /etc/rc.d/rc.local slack2:/etc/rc.d/
scp /etc/rc.d/rc.local slack3:/etc/rc.d/
scp /etc/rc.d/rc.local_shutdown slack2:/etc/rc.d/
scp /etc/rc.d/rc.local_shutdown slack3:/etc/rc.d/
all nodes (including the diskless one)
initialize the underlying physical disks and enable the replicated volume
drbdadm create-md slack drbdadm up slack ls -lF /dev/drbd1
slack1
state is currently inconsistent on both sides of the mirror.
drbdadm status
since this is a clean and initial shot (there’s no data at all) we can proceed with a quick trick
a single time, on any node
drbdadm new-current-uuid --clear-bitmap slack
–otherwise– we would we need to enforce and mark a valid state somewhere to begin with.
#drbdadm primary --force slack
and so forth with the other nodes hosting a primary DRBD device.
now check the the nodes are synchronizing
drbdadm status
using the clear-bitmap trick, you won’t loose the sparse on the secondary volume
slack2
lvs -o+discards thin
the init script was already enabled at startup
ls -lF /etc/rc.d/init.d/drbd cat /etc/rc.d/rc.local cat /etc/rc.d/rc.local_shutdown
check what protocol the resource is living upon
v8
cat /proc/drbd
v9
drbdsetup show all --show-defaults | grep proto
v9 (as long as debug is enabled)
cat /sys/kernel/debug/drbd/resources/<resource>/connections/<connection>/<volume>/proc_drbd
and last but not least, check that you can access the DRBD diskless device from slack3.
check that the replicated volumes are brought up after a reboot
reboot
see operations
root@slack1:~# drbdadm primary --force slack slack: State change failed: (-7) Refusing to be Primary while peer is not outdated Command 'drbdsetup primary slack --force' terminated with exit code 11
==> slack resource on slack3 was not up (and although it’s diskless)
LINBIT DRBD kernel module https://github.com/LINBIT/drbd
DRBD userspace utilities (for 9.0, 8.4, 8.3) https://github.com/LINBIT/drbd-utils
“read-balancing” with 8.4.1+ https://www.linbit.com/en/read-balancing/
The DRBD9 User’s Guide https://linbit.com/drbd-user-guide/drbd-guide-9_0-en/ ==> 4.1.8 initial sync
DRBD 9.0 Manual Pages https://docs.linbit.com/man/v9/
drbd.conf - DRBD Configuration Files https://docs.linbit.com/man/v9/drbd-conf-5/
DRBD 8.4 https://github.com/LINBIT/drbd-8.4
drbd.conf - Configuration file for DRBD’s devices https://docs.linbit.com/man/v84/drbd-conf-5/
How to Install DRBD on CentOS Linux https://linuxhandbook.com/install-drbd-linux/
How to Setup DRBD 9 on Ubuntu 16 https://www.globo.tech/learning-center/setup-drbd-9-ubuntu-16/
LINSTOR SDS server https://github.com/LINBIT/linstor-server
CLI management tool for DRBD. Like top, but for DRBD resources. https://github.com/LINBIT/drbdtop
[DRBD-user] drbd-dkms fails to build under proxmox 6 https://lists.linbit.com/pipermail/drbd-user/2019-August/025208.html
[DRBD-user] Problems compiling kernel module https://lists.linbit.com/pipermail/drbd-user/2016-June/022391.html
5.4.4. Creating Thinly-Provisioned Logical Volumes https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/logical_volume_manager_administration/thinly_provisioned_volume_creation
How to setup thin Provisioned Logical Volumes in CentOS 7 / RHEL 7 https://www.linuxtechi.com/thin-provisioned-logical-volumes-centos-7-rhel-7/
Thin Provisioning in LVM2 https://www.theurbanpenguin.com/thin-provisioning-lvm2/
Setup Thin Provisioning Volumes in Logical Volume Management (LVM) – Part IV https://www.tecmint.com/setup-thin-provisioning-volumes-in-lvm/
https://linbit.com/blog/drbd-linstor-vs-ceph/
https://linbit.com/blog/drbd-vs-ceph/
https://linbit.com/blog/how-does-linstor-compare-to-ceph/
RDMA NIC Latest Updates¶ http://lastweek.io/notes/source_code/rdma/