DRBD

Distributed Replicated Block Device

Links

• Homepage
• DRBD + pacemaker + NFS, pretty good doc
• http://www.securityandit.com/system/pacemaker-cluster-with-nfs-and-drbd/
• Integrating DRBD with Pacemaker clusters
• https://www.sebastien-han.fr/blog/2012/08/01/corosync-rrp-configuration/
• Building a redundant pair of Linux storage servers using DRBD and Heartbeat
• [https://serverstack.wordpress.com/2017/05/31/install-and-configure-drbd-cluster-on-rhel7-centos7/
• http://www.asplund.nu/xencluster/page2.html
• Resizing resources
• http://www.linux-ha.org/wiki/Main_Page

• Configure sync rate
• https://serverfault.com/questions/740311/drbd-terrible-sync-performance-on-10gige
• also tuning tips
• Debian DRBD: How to resize NFS on drbd volume on top of LVM

See also: http://www.gluster.org/ and http://ceph.com/

• Xen and DRBD

Stacked resources

• DRBD 8.3 Third Node Replication (stacked)
• Resource stacking

Support

• Linbit
• Hastexo

Tools

• LCMC, a GUI for managing LVM, DRBD in pacemaker environment]
• zabbix monitoring for drbd

Docs

• Resizing drbd xen lvm (dont worry about the meta-data if that's not internal) (bug it seems wrong, using phy: instead of drbd: )
• http://www.asplund.nu/xencluster/page2.html

Recovery

• Recovering from a DRBD split-brain scenario in heartbeat
• http://www.asplund.nu/xencluster/page2.html
• [https://docs.linbit.com/doc/users-guide-83/s-split-brain-notification-and-recovery/ Split brain notification and automatic recovery
• Troubleshooting DRBD on MediaCentral

GFS on DRBD

• http://sourceware.org/cluster/wiki/DRBD_Cookbook
• http://www.piemontewireless.net/Storage_on_Cluster_DRBD_and_GFS2

Cheatsheet

Make device primary

drbdadm primary yourdeviceID

or

drbdsetup /dev/drbdX primary -o

Grow resource

On both nodes:

lvextend -L+10G /dev/DRBD/myresource

On one node:

drbdadm resize myresource

FAQ

1: State change failed: (-2) Need access to UpToDate data

when you get that tryinng to make a node/resource primary, try

drbdadm primary drbdX --force

show resource sizes

lsblk

commands to show info

drbdmon
drbdtop

resolving split brain issues

• https://docs.linbit.com/doc/users-guide-83/s-resolve-split-brain/
• https://www.sebastien-han.fr/blog/2012/04/25/DRBD-split-brain/

diskless

You might try

drbdadm attach drbd0

sync is slow

• https://forum.proxmox.com/threads/slow-drbd9-sync-like-20mbit-on-1gbit.27927/
• Configuring sync rate

Show current settings:

drbdsetup show

On secondary:

drbdadm disk-options --c-plan-ahead=0 --resync-rate=50M drbd0and 

and to reset after sync:

drbdadm adjust drbd0

show configuration

drbdsetup show

show more info

drbdsetup show-gi <minor-number>

update network settings

drbdsetup net-options 10.0.0.1 10.0.0.2  --sndbuf-size=2M

mount: unknown filesystem type 'drbd'

Usually means your node is not primary. If you're sure you know what you're doing you can use

mount -t ext4 /dev/drbd1 /drbdmount

reload configuration

drbdadm adjust all

show configuration of resource

drbdsetup /dev/drbd0 show

resource unknown

First try

drbdadm up resourcename

Command 'drbdmeta 1 v08 /dev/drbd0 internal apply-al' terminated with exit code 20

Most likely split brain issue, check dmesg etc