On 8/4/10, Todd Denniston <Todd.Denniston@xxxxxxxxxxxxxxxxxxxxx> wrote:
> To have more than one active server with DRBD (or other disk type shared
> between active machines)
> you need to be using a file system which supports shared disk resources.
> http://www.drbd.org/docs/about/
> http://www.drbd.org/users-guide-emb/s-dual-primary-mode.html
> http://www.drbd.org/users-guide-emb/ch-gfs.html
> http://www.drbd.org/users-guide-emb/ch-ocfs2.html
>
> and perhaps using Gluster (Raid0 on net) with DRBD (Raid 1 on net) as disk
> space to get HA into Gluster?
> http://www.drbd.org/users-guide-emb/ch-xen.html
>
Thanks for pointing it out, I didn't realize drdb could do that. I
think I might have gotten it mixed up earlier with a thread that
discussed using rsync.
That said, wouldn't using gluster alone be easier to configure and
cheaper for almost equivalent redundancy?
Easier because instead of running gluster raid 0 on top of DRBD raid
1, we can take out the DRBD layer and just use gluster to achieve the
equivalent by distribute on replicate.
More importantly there is the issue of cost, DRBD needs a pair of
server per node for active-active. However, gluster allows me to get
RAID "0.67" redundancy by "round robin" replicate.
i.e. If every storage node has 2 mdraid 1 block devices md0 and md1, I
can mirror Server1 md0 to Server2 md1, Server2 md0 to Server3 md1 and
so forth. Theoretically capable of surviving up to 50% node failure if
no two adjacent node fails together. This for the cost of N+1 as
compared to DRBD's Nx2 cost.
Please correct me if I miss out some other crucial consideration.
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