On 4/4/19 5:52 am, JCA wrote:
My apologies for the length of this; I'd rather give to much
information than too little.
I have a simple PaceMaker cluster with two nodes, A and B, that are
CentOS 7 VMs. In both nodes I have a file named my-data.res under
/etc/drdb.d, with the following contents (identical in both nodes):
resource my-data {
protocol C;
meta-disk internal;
device /dev/drbd1;
syncer {
verify-alg sha1;
}
net {
allow-two-primaries;
}
on A {
disk /dev/sdb1;
address 192.168.0.5:7789 <http://192.168.123.17:7789>;
}
on B {
disk /dev/sdb1;
address 192.168.0.6:7789 <http://192.168.123.20:7789>;
}
}
In both A and B, I did the following:
# drbdadm create-md my-data
--== Thank you for participating in the global usage survey ==--
The server's response is:
you are the xxxxxth user to install this version
drbdmeta 1 v08 /dev/sdb1 internal create-md
# drbdadm up my-data
In A alone, I did the following:
# drbdadm primary --force my-data
After this, and giving time for both nodes to become synchronized, I
get the following in A:
# cat /proc/drbd
version: 8.4.11-1 (api:1/proto:86-101)
GIT-hash: 66145a308421e9c124ec391a7848ac20203bb03c build by
mockbuild@, 2018-11-03 01:26:55
1: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C
r-----ns:2096028 nr:0 dw:0 dr:2098148 al:8 bm:0 lo:0 pe:0 ua:0 ap:0
ep:1 wo:f oos:0
whereas the output from the same command in B is
version: 8.4.11-1 (api:1/proto:86-101)
GIT-hash: 66145a308421e9c124ec391a7848ac20203bb03c build by
mockbuild@, 2018-11-03 01:26:55
1: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C
r-----ns:0 nr:2096028 dw:2096028 dr:0 al:8 bm:0 lo:0 pe:0 ua:0 ap:0
ep:1 wo:f oos:0
In A, I then created a filesystem in the /dev/drbd1 device
# mkfs.ext4 /dev/drbd1
I then mounted it (stil in A) and populated it with some data,
consisting of two files, f1 and f2, unmounting when done.
After this, I issued the following commands in A:
# pcs cluster cib drbd_cfg
# pcs -f drbd_cfg resource create DrbdData ocf:linbit:drbd
drbd_resource=my-data op monitor interval=60s
# pcs -f drbd_cfg resource master DrbdDataClone DrbdData
master-max=1 master-node-max=1 clone-max=2 clone-node-max=1 notify=true
# pcs cluster cib-push drbd_cfg
# pcs cluster cib fs_cfg
# pcs -f fs_cfg resource create DrbdFS Filesystem
device="/dev/drbd1" directory="/var/lib/my-data" fstype="ext4"
# pcs -f fs_cfg constraint colocation add DrbdFS with
DrbdDataClone INFINITY with-rsc-role=Master
# pcs -f fs_cfg constraint order promote DrbdDataClone then
start DrbdFS
Adding DrbdDataClone DrbdFS (kind: Mandatory) (Options:
first-action=promote then-action=start)
# pcs -f fs_cfg constraint colocation add ClusterIP with
DrbdFS INFINITY
# pcs -f fs_cfg constraint order DrbdFS then ClusterIP
Adding DrbdFS ClusterIP (kind: Mandatory) (Options:
first-action=start then-action=start)
# pcs cluster cib-push fs_cfg
CIB Updated
# pcs status resources
ClusterIP (ocf::heartbeat:IPaddr2): Started A
Master/Slave Set: DrbdDataClone [DrbdData]
Masters: [ A ]
Slaves: [ B ]
DrbdFS (ocf::heartbeat:Filesystem): Started A
The output from the last command in B is very similar, mutatis mutandis.
Once this all is done, node A is active where node B is passive. When
I do
# ls /var/lib/my-data
in A I can see the f1 and f2 files that I created above. In B,
however, there is nothing. My understanding of the DRBD framework
tells me that this is expected.
During this state of affairs (i.e. the cluster up both in A and B,
with A being the active node and B being the passive node) I stopped
the A node by issuing the following command in A:
# pcs cluster stop A
After this, and giving time for node B to take over, I get the
following in B:
# pcs status
Cluster name: FirstCluster
Stack: corosync
Current DC: B (version 1.1.19-8.el7_6.4-c3c624ea3d) -
partition with quorum
Last updated: Wed Apr 3 11:49:19 2019
Last change: Wed Apr 3 09:53:30 2019 by root via cibadmin
on B
2 nodes configured
4 resources configured
Online: [ B ]
OFFLINE: [ A ]
Full list of resources:
ClusterIP(ocf::heartbeat:IPaddr2):Started B
Master/Slave Set: DrbdDataClone [DrbdData]
Masters: [ B ]
Stopped: [ A ]
DrbdFS(ocf::heartbeat:Filesystem):Started B
Daemon Status:
corosync: active/enabled
pacemaker: active/enabled
pcsd: active/enabled
On listing the contents of /var/lib/my-data on A, nothing is found
there. However, on listing the contents of /var/lib/my-data on B, I
find files f1 and f2. So, B has taken over and is now accessing,
thanks to DRDB, the filesystem created in A earlier on.
Next I started and stopped both A and B (the nodes, not the VMs) until
I got back the original situation - namely, A is active, B is passive,
/var/log/my-data contains f1 and f2 in A, and nothing in B.
Next I did the following: In A I removed both f1 and f2, and added new
files, f3, and f4. I did this while A is the active node. After this I
stopped the A node from A as above. Having done this, the output from
pcs status in B is as described above. Here's the thing:
In this situation, when I list the contents of /var/lib/my-data in A,
I find it to be empty - as expected, for A has been stopped. When I
list the contents of /var/lib/my-data in B, however, what I see is
files f1 and f2, not f3 and f4. I was expecting for any changes made
on /var/lib/my-data while A was active to be made visible to B when it
takes over.
Is my expectation misplaced? Or perhaps the changes to
/var/lib/my-data have to be made by some resource explicitly managed
by PaceMaker, while changes done by hand are just dismissed? Notice,
however, that if I bring the A node up again, and make it active, on
listing /var/lib/my-data on A I see files f3 and f4: the changes I
made by hand have not just been dismissed.
As you can see, I am very confused.
I have no idea what all your cluster management commands do, but it
sounds like you are mounting the underlying device on A instead of the
DRBD device. Thus, the changes you make are not replicated to B.
While A is active and you see f3 and f4, run df /var/lib/my-data and
provide the output here, or just note that if the device is not
/dev/drbd<something> then you have made this mistake.
Hope that this helps...
Regards,
Adam
--
The information in this e-mail is confidential and may be legally privileged.
It is intended solely for the addressee. Access to this e-mail by anyone else
is unauthorised. If you are not the intended recipient, any disclosure,
copying, distribution or any action taken or omitted to be taken in reliance
on it, is prohibited and may be unlawful. If you have received this message
in error, please notify us immediately. Please also destroy and delete the
message from your computer. Viruses - Any loss/damage incurred by receiving
this email is not the sender's responsibility.
--
Adam Goryachev Website Managers www.websitemanagers.com.au
_______________________________________________
drbd-user mailing list
[email protected]
http://lists.linbit.com/mailman/listinfo/drbd-user
