[DRBD-user] Strange behaviour of DRBD

Romain Pelissier romain.pelissier at gmail.com
Tue Oct 4 16:58:49 CEST 2016

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

So first, sorry if you foud this question basic but I am very new to drbd.
Second, maybe it's perfectly normal but in this case, I will need some
advices from you gyus :)

Here is my situation:

I use 8.4.7-1 on RHEL 6.5 (2.6.32-642.4.2.el6.x86_64) on my 2 nodes. I use
drbd with this scenario:

I have an lvm partition formatted as xfs.
 This partition contain ma application database (several Gigs).
I want to use drbd to have a copy of the partition on the remote node.

Here is my conf:

cat /etc/drbd.d/backup.res
global { usage-count no; }
common { syncer { rate 1000M; } }
resource rc0 {
        protocol C;
        startup {
                wfc-timeout  15;
                degr-wfc-timeout 60;
        net {
                cram-hmac-alg sha1;
                shared-secret "secret2secret";
        on esm65 {
                device /dev/drbd0;
                disk /dev/vg0/lv_arc;
                #meta-disk internal;
                #flexible-meta-disk /dev/vg0/lv_drdb_md;
                meta-disk /dev/vg0/lv_drdb_md;
        on phpesmbck01 {
                device /dev/drbd0;
                disk /dev/vg0/lv_arc;
                #meta-disk internal;
                #flexible-meta-disk /dev/vg0/lv_drdb_md;
                meta-disk /dev/vg0/lv_drdb_md;

The first sync works fine. To test it once completed, I stop drbd on thr
second node, mount /dec/vg0/lv_arc on a folder and I can see the folders.
For the fun of it, I have renoved a folder on the secondary node drbd
partition (drbd was stop at that time). then umount it and start drbd

I check this

cat /proc/drbd
version: 8.4.7-1 (api:1/proto:86-101)
GIT-hash: 3a6a769340ef93b1ba2792c6461250790795db49 build by
mockbuild at Build64R6, 2016-01-12 13:27:11
 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
    ns:72054328 nr:0 dw:19012784 dr:59035232 al:1170 bm:0 lo:0 pe:0 ua:0
ap:0 ep:1 wo:f oos:0

So, everything seems to be up to date.
But If I stop the seocndary node, mount the lvm in a folder, the folder
that I have deleted earlier is not there but it exists on the primary node.

Is it normal in this case that the status is UpToDate/UpToDate? How can I
be sure that the 2 partition are really in sync?

Thanks for your explanation!

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