[Ocfs2-users] Soft and Hard Readonly?

[Alexei Roudnev]

If disk is readonly, then you dont need custer file system at all - create
ext3 or reiserfs FS and use it.

Idea, as I can see, is in allowing one node to update and other to read
only, but keep overall stability as in non-clustered FS (clustered FS in
unstable beast by definition, because of many possible split-brain
scenarios, fencings and so on).

Allowing other nodes to run heartbeat means, again, the same
quorum/fencing/timeouts problems which we have on all cluster file systems,
and which are extremely serious on OCFS2.


----- Original Message ----- 
From: "Sutterfield, Geary L." <glsutter at mitre.org>
To: "Sunil Mushran" <Sunil.Mushran at oracle.com>
Cc: <ocfs2-users at oss.oracle.com>
Sent: Monday, November 13, 2006 3:07 PM
Subject: RE: [Ocfs2-users] Soft and Hard Readonly?


By "actual readonly" I assume you mean at the hardware level. So a disk
connected via a SAN could use soft readonly but not hard readonly. And
that would mean a heartbeat would be started. And that would mean the
node could be fenced. Does that sound correct?

Geary Sutterfield
Lead Software Systems Engineer
Software Solutions and Technology
The MITRE Corporation
703-983-5667

-----Original Message-----
From: Sunil Mushran [mailto:Sunil.Mushran at oracle.com]
Sent: Monday, November 13, 2006 4:39 PM
To: Sutterfield, Geary L.
Cc: ocfs2-users at oss.oracle.com
Subject: Re: [Ocfs2-users] Soft and Hard Readonly?

To mount readonly, do:
mount -o ro /dev/sdX /dir

The difference between soft and hard is that in the latter the
heartbeat
is not
started. Meaning no need to join a dlm domain. The latter only works on
actual readonly devices.

Sutterfield, Geary L. wrote:
> I've seen some discussions in the past about "soft readonly" and
"hard
> readonly" options in OCFS2. But I can't seem to find a description of

> them anywhere. Do I have look at code comments? Or is there another
> place that describes how these work? Are they mount options?
>
> I'm trying to configure a cluster with a single write-enabled server
> and multiple read-only servers. Does anyone have experience with this

> type of configuration? Can the hard readonly or soft readonly options

> be used to create such a configuration? If anyone has any experience
> setting up a cluster like this, I'd like to hear about your
> configuration and your experiences.
>
> Thanks
>
> Geary Sutterfield
> Lead Software Systems Engineer
> Software Solutions and Technology
> The MITRE Corporation
>
>
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