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List:       ocfs2-devel
Subject:    Re: [Ocfs2-devel] OCFS2 with global heartbeat on DRBD devices
From:       "Gang He" <ghe () suse ! com>
Date:       2019-05-06 3:07:13
Message-ID: 5CCFA4E1020000F90006408F () prv1-mh ! provo ! novell ! com
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Hi Daniel,

Just give some comments from my view,
1) in technically, DRBD presents a block device, OCFS2 file system can use this block \
as its shared storage, there should not be any problem to set up a ocfs2 cluster. 2) \
Based on my understanding, DRBD usually provide a primary-slaver block device, but \
ocfs2 should need to a real shared storage, since all nodes access this shared disk \
simultaneously.  I feel that DRBD does NOT handle this case under heavy pressure, \
though DRBD has double-primary feature.

Thanks
Gang  

> > > On 2019/5/5 at 16:19, in message
<b661cdca-05ae-7b70-f768-ea49dfb66a64@gmail.com>, Joseph Qi
<jiangqi903@gmail.com> wrote:
> Cc ocfs2-tools-devel.
> 
> Hi Daniel,
> I don't have experience on using global heartbeat on DRBD device.
> But from my understanding, I don't think there is any restriction for this 
> use case.
> 
> Thanks,
> Joseph
> 
> On 19/5/3 20:54, Daniel Sobe wrote:
> > Hi,
> > 
> > I'm wondering why the current version of the "o2cb" tool does not support 
> global heartbeat on DRBD devices.
> > 
> > Do I misunderstand the feature "global heartbeat" in that I should not use 
> it on DRBD at all?
> > 
> > I patched the "o2cb" tool to recognize DRBD devices for starting a global 
> heartbeat. Now the global heartbeat configuration with DRBD seems to work at 
> cluster start, but I wonder whether it really is that easy - or I am just 
> missing something. Maybe it failed silently and I did not notice?
> > 
> > BTW I edited file "o2cb_scandisk.c" function "add_to_list()" like this:
> > 
> > if (!add)
> > add = 
> !strncmp(path->path, "/dev/rbd", 8);
> > if (!add) // added
> > add = 
> !strncmp(path->path, "/dev/drbd", 9); // added
> > 
> > and by observing the output of "/proc/drbd" I can tell that the stats for 
> data read and data written on the DRBD device for the global heartbeat 
> increases, while it stays the same on all other DRBD devices. (I have not 
> mounted any of these volumes)
> > 
> > To me it looks like it works. Can anybody comment? Can I somehow "observe" 
> the proper operation of the global heartbeat?
> > 
> > Regards,
> > 
> > Daniel
> > 
> > 
> > 
> > _______________________________________________
> > Ocfs2-devel mailing list
> > Ocfs2-devel@oss.oracle.com 
> > https://oss.oracle.com/mailman/listinfo/ocfs2-devel 
> > 
> 
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel@oss.oracle.com 
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel


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