DRBD

Distributed Replicated Block Device

Links

• Homepage
• DRBD-8.4 user's guide
• DRBD + pacemaker + NFS, pretty good doc
• http://www.securityandit.com/system/pacemaker-cluster-with-nfs-and-drbd/
• 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
• DRBD cheat sheet
• http://www.linux-ha.org/wiki/Main_Page
• HA iSCSI with drbd and pacemaker
• Internal meta data

• 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
• HOWTO: Resolve DRBD split-brain recovery manually

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

• Xen and DRBD

Stacked resources

• Using stacked DRBD resources in Pacemaker clusters
• https://github.com/fghaas/drbd-documentation/blob/master/users-guide/pacemaker.txt
• Pacemaker and DRBD9 stacked resources
• DRBD 8.3 Third Node Replication (stacked)

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

Check resource file

Editing files in /etc/drbd.d/ is a bad plan, to check syntax first:

drbdadm dump -c /tmp/test.res

FAQ

Get out of 'Standalone'

disconnect/connect until works :)

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

calculate metadata size

https://serverfault.com/questions/433999/calculating-drbd-meta-size

Cs=`blockdev --getsz /dev/foo`
Bs=`blockdev --getpbsz /dev/foo`

TODO finish this

'mydrbd' not defined in your config (for this host).

If drbdadm create-md throws this, 'this host' is the clue: it must match `hostname`

https://newbiedba.wordpress.com/2015/09/21/drbd-not-defined-in-your-config-for-this-host/

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

The disk contains an unclean file system (0, 0).

Metadata kept in Windows cache, refused to mount. Falling back to read-only mount because the NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting.)

When trying to mount a snapshot (kpartx -av backup-snap1 etc)

???

sync is slow

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

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>

Minor number is shown in drbdsetup show

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

or when you want to mount the partion while drbd is down:

kpartx -av /dev/mapper/DRBD-test1 
#add map DRBD-test1p1 (253:5): 0 10482928 linear /dev/mapper/DRBD-test1 2048
#I suggest mounting ro 
mount -o ro /dev/mapper/DRBD-test1o1 /mnt/test1

reload configuration

drbdadm --dry-run adjust <resourcename|all>

and then

drbdadm adjust <resourcename|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

wfconnection

Could be split brain situation

drbdadm -- --discard-my-data connect resource

cs:StandAlone ro:Primary/Unknown ds:UpToDate/DUnknown

So you're on the primary node, secondary might showing nothing, then first

drbdadm up drbdX

or if secondary shows "cs:WFConnection ro:Secondary/Unknown ds:UpToDate/DUnknown", it is waiting for connection(no?)

drbdadm disconnect drbdres
drbdadm connect --discard-my-data drbdres

or it shows "cs:WFConnection ro:Secondary/Unknown ds:UpToDate/DUnknown", in that case what might work on primary node:

drbdadm disconnect drbdX
drbdadm connect drbdX

Split brain issue

To force updating resource

drbdadm invalidate resource

cs:WFReportParams ro:Secondary/Unknown ds:UpToDate/DUnknown

connection is made, waiting for more

Unexpected data packet AuthChallenge (0x0010)

maybe the shared key

State change failed: Device is held open by someone

could be stacked resource, timeout?

error receiving ReportState, e: -5 l: 0!

??

drbd: error sending genl reply

CentOS feature, https://wiki.centos.org/Manuals/ReleaseNotes/CentOS7.2003. "Try another kernel/module version"

State change failed: (-14) Need a verify algorithm to start online verify

Means no verify-alg was defined, so no online checking

drbdadm dump-md foo: Found meta data is "unclean", please apply-al first

Try

drbdadm apply-al foo

( AL means "activity log", btw )