[DRBD-user] Strange behaviour of DRBD

[Kesch, Matthias]

Congratz…

If you see such an output then you accomplished to break the filesystem.
Don´t mess around with the DRBD-System by doing such things you described.

If want to check proper DRBD-Sync, just promote/demote the desired partition with drbdtools and mount it. Don´t do anything under the layer of DRBD. You saw what happens otherwise.


--

Mit freundlichen Grüßen / Kind Regards
Matthias Kesch

Von: drbd-user-bounces at lists.linbit.com [mailto:drbd-user-bounces at lists.linbit.com] Im Auftrag von Romain Pelissier
Gesendet: Dienstag, 4. Oktober 2016 19:36
An: drbd-user at lists.linbit.com
Betreff: Re: [DRBD-user] Strange behaviour of DRBD

Hi,
I have also noticed that after a while, the folder I have delete previously on the secondo node appear again but.. in a strange form:


???????????  ? ?    ?       ?            ? web
drwxr-xr-x.  8  501  501   97 Sep 15 17:09 services/

Has you can see, the folder seems to exist but I can't access it at all.
Is it a normal behaviour?

Thanks


2016-10-04 10:58 GMT-04:00 Romain Pelissier <romain.pelissier at gmail.com<mailto:romain.pelissier at gmail.com>>:
Hi,
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;
                address 172.31.254.27:7788<http://172.31.254.27:7788>;
                #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;
                address 172.31.254.19:7788<http://172.31.254.19:7788>;
                #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.
Perferct!
But..
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 process.

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!
Romain


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