[Gluster-devel] Server-side AFR + Failover and mixed server/client-side AFR
Krishna Srinivas
krishna at zresearch.com
Tue May 6 15:40:53 UTC 2008
On Tue, May 6, 2008 at 9:09 PM, Krishna Srinivas <krishna at zresearch.com> wrote:
> On Tue, May 6, 2008 at 9:04 PM, <gordan at bobich.net> wrote:
> > On Tue, 6 May 2008, Krishna Srinivas wrote:
> >
> >
> > >
> > > > If server-side AFR breaks with fail-over, is it possible to use
> > server-side
> > > >
> > > > AFR on some nodes and client-side AFR on others, with the client side
> > AFR
> > > > nodes talking directly to the same storage bricks that the server side
> > AFR
> > > > is unifying for server-side AFR nodes?
> > > >
> > > > Or would this break things?
> > > >
> > >
> > >
> > > It will not break things as long as the afr's subvol listing order are
> > same.
> > >
> >
> > Is this an issue in server-side-only AFR? I have two servers which are also
> > clients of themselves, and they both list their local subvolume first and
> > remote subvolume second. Is this a problem? What are the possible
> > consequences of this?
>
> It will be a problem. The "first" subvol is always the "lock" server.
> Consider a case where you are creating a file simultaneously
> on two clients, only one of them should succeed. If AFR's
> subvols order are not same, chances are that both client
> returns success for file creation with same name.
Hence you have "option read-subvlume" to speeden the
read() calls so that it can be done from local subvol.
>
> Krishna
>
>
>
>
> >
> >
> >
> > Gordan
> >
> >
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> > http://lists.nongnu.org/mailman/listinfo/gluster-devel
> >
>
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