Questions[cluster](server)

I have a Redis cluster with the following nodes:

192.168.0.14:6379 master (slots from 0 to 16383)
192.168.0.15:6379 slave (slots from 0 to 16383)
192.168.0.16:6379 master (without slots)

Documentation says that any node can redirect queries to the properly node. But I can not redirect requests from 192.168.0.16:6379 master node. Here is what I tried:

192.168.0.16:6379> set myKey myValue
(error) MOVED 16281 192.168.0.14:6379
192.168.0.16:6379> get myKey
(error) MOVED 16281 192.168.0.14:6379

It neither writes nor reads. When I try to get "myKey" from 192.168.0.14:6379 it shows next:

127.0.0.1:6379> get myKey
(nil)

What is wrong with my requests? I am using redis server version 3.2.5

I am currently thinking about migrating some of our servers and apps to a coreOS environment. One of the problems I see here is the management of persistent data as coreOS does not handle Docker volumes when moving a container to a new machine. After some research I found glusterFS which claims to be a cluster file system that could solve all my problems.

My current idea is this: I have a glusterFS container which runs as a privileged container on each of my coreOS machines and exposes a storage, /mnt/gluster, for example. In my Dockerfiles I specify that all my volumes should be mounted on this path.

The next thing I considered was which containers should obtain their own volumes and which ones should be sharing one. For example, every mysql container would get its own volume as it is able to handle replication by itself. I don't want to mess around with that. Webservers serving the same website would properly use the same volume for stuff like "user uploaded images", etc. as they are not able to replicate those data.

Has anybody tried something like this or is there anything I have missed?

I'm using nginx and NginxHttpUpstreamModule for loadbalancing. My config is very simple:

upstream lb {
    server 127.0.0.1:8081;
    server 127.0.0.1:8082;
}

server {
    listen  89;
    server_name localhost;

    location / {
            proxy_pass      http://lb;
            proxy_redirect  off;
            proxy_set_header        Host            $host;
            proxy_set_header        X-Real-IP       $remote_addr;
            proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

But with this config, when one of 2 backend server is down, nginx still routes request to it and it results in timeout half of the time :(

Is there any solution to make nginx to automatically route the request to another server when it detects a downed server.

Thank you.

Puppet requires certificates between the client (puppet) being managed and the server (puppetmaster). You can run manually on the client and then go onto the server to sign the certificate, but how do you automate this process for clusters / cloud machines?

Are there any production-quality iSCSI SANs suitable for use with Windows Server 2008/SQL Server for failover clustering?

So far, I've only seen Dell's MD3000i, and HP's MSA 2000 (2012i), which both are around $6K with a minimal disk configuration. Buffalo (yea, I know), has a $1000 device with iSCSI support, but they say it will not work for 2008 failover clustering.

I'm interested in seeing something suitable for failover in a production environment, but with very low IO requirements. (Clustering, say, a 30GB DB.)

As for using software: On Windows, StarWind seems to have a great solution. But it's actually more money than buying a hardware SAN. (As I understand, only the enterprise edition supports having replicas, and that's $3000 a license.)

I was thinking I could use Linux, something like DRBD + an iSCSI target would be fine. However, I haven't seen any free or low-cost iSCSI software that supports SCSI-3 persistent reservations, which Windows 2008 needs for failover clustering.

I know $6K isn't much at all, just curious to see if there are practical cheaper solutions out there. And finally, yes, the software is expensive, but many small business get MS BizSpark, so the Windows 2008 Enterprise / SQL 2008 licenses are completely free.