[Gluster-devel] replicate with 5 nodes - and adding more nodes in the future

[Krishna Srinivas]

correcting a typo :-(

On 6/25/07, Krishna Srinivas <krishna at zresearch.com> wrote:
> On 6/25/07, Shai DB <dbshai at gmail.com> wrote:
> > Hello, we are testing glusterfs 1.2 and I have few questions -
> >
> >
> > 1. we are going to store millions of small jpg files that will be read by
> > webserver - is glusterfs good solution for this ?
>
> Yes, definitely.
>
> > 2. we are going to run both server+clients on each node together with apache
> >
> > 3. replicate *:2
> >
> > the way i think doing replicate is defining on each server 2 volumes and
> > using AFR:
> >
> > server1: a1, a2
> > server2: b1, b2
> > server3: c1, c2
> > server4: d1, d2
> > server5: e1, e2
> >
> > afr1: a1+b2
> > afr2: b1+c2
> > afr3: c1+d2
> > afr4: d1+e2
> > afr5: e1+a2
> >
> > and then unify = afr1+afr2+afr3+afr4+afr5 with replicate option
> >
> > is this correct way ?
> > and what to do on the future when we add more nodes ? when changing the afr
> > (adding and changing the couples) making glusterfs
> > redistribute the files the new way ?
>
> Yes this is the right way. If you add one more server f, the one solution
> is to move contents of a2 to f2 and clean up a2 and have it as following:
>
> afr5: e1 + f2
> afr6: f1 + a2
>
> Cant think of an easier solution.
>
> But if we assume that you will always add 2 servers when you want to add,
> we can have the setup in following way:
> afr1: a1 + b2
> afr2: b1 + a2
> afr3: c1 + d2
> afr4: d1 + c2
> afr5: e1 + f2
> afr6: f1 + e2
>
> Now when you add a pair of servers to this (g, h):
> afr7: f1 + h2
> afr8: h1 +f2

afr7: g1 + h2
afr8: h1 +g2

>
> Which is very easy. But you will have to add 2 servers everytime.
> The advantage is that it is easier to visualize the setup and add
> new nodes.
>
> Thinking further, if we assume that you will replicate all the files
> twice (option replicate *:2) you can have the following setup:
> afr1: a + b
> afr2: c + d
> afr3: e + f
>
> This is a very easy setup. It is simple to add a fresh pair (afr4: g +h)
>
> You can have whatever setup you want depending on your
> convinience and requirement.
>
> >
> > 4. what happens when a hard drive goes down and replaces, the cluster also
> > redistribute the files ?
>
> When a hard drive is replaced, missing files will be replicated from the
> AFR's other child.
>
> Regards
> Krishna
>
> -------
>
> The best quote ever : '
>