brianu wrote:
Hello all,
This is a question I have basically been asking, the question on why
you would want to do it is failover, the docs at
http://sourceware.org/cluster/gnbd/gnbd_usage.txt state that
dm-multipath is an option for gnbd,
I'm not sure about dm-multipath. The thing is, when a gnbd server dies,
instead of saying "read/write failed" as normal block device does, gnbd
simply retries the request and tries to reconnect if it's disconnected.
Forever.
and documents elsewhere also indicate that GNBD can be configured as a
redundancy, yet I cannot find any documentation on how to configure it.
If using LVM to make a volume of imported gnbds is not the answer for
redundancy can anyone suggest a method that is? Im not opposed to
using any other resource of cluster or GFS but I would really like to
implement a redundant solution, ( gnbd, gulm, etc.).
It would be possible if you have at least two servers, connected to the
same storage, running as gnbd server and exporting the same block devices.
You need to have one IP address that can failover to any available node
(use rgmanager or keepalived to achieve this). That way, if one server
node dies the IP address will be moved to the other node. Client will be
disconnected, but since gnbd-import will automatically reconnect (it
actually connects to a different node since the gnbd server IP address
was moved) the process will be transparent to the client (all they see
is a slight delay during reconnect).
Regards,
Fajar
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