Mick Pollard wrote:
On Sat, 05 Apr 2008 09:52:55 +1100
Crossfire <[EMAIL PROTECTED]> wrote:
I've just spent some time quickly researching this to no real satisfaction.
What I'm looking for is a way to do real-time hot-replication of a whole
filesystem or filesystem tree over 2 nodes (and strictly 2 nodes)
without STOMITH[1].
The scenario is I have two identical systems with local (software)
RAID1. They will be tethered onto their internet feed via ethernet, and
can optionally be tethered to each other via Gig.
Have you had a look at http://www.drbd.org/ ?
It basically mirrors a blockdevice over ethernet.
A raid1 of sorts.
DRBD doesn't actually solve the problem - it either provides a warm
replication of a normal filesystem, or provides an pseudo-shared storage
device.
Warm replication is a no-go since I will need effectively local access
to the filesystem on both nodes so there isn't a song-and-dance routine
to perform w.r.t mounts, etc, during a failure.
As a psuedo-shared storage device, I doubt it's of any particular use
due to (drastically-higher) latency incurred by having to replicate the
changes between the storage pools rather than the storage pool being
shared. I'd also be concerned about split-brain recovery with cluster
filesystems (split-brain is not actually possible with a real shared
drive, but completely possible with DRBD). Initial comments I've seen
from people trying to use it with OCFS2 also seem poor.
C.
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