A computer cluster consists of a set of loosely connected computers that work together so that in many respects they can be viewed as a single system.

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How to set up Zabbix to monitor SQL Server Failover Active-Passive Cluster?

It should be simple, so it is just most likely my approach being totally off and someone will hopefully prod me into the right direction. We have a Zabbix 2.0.3 server instance set up monitoring a ...
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how to do automatic failover of mysql / galera cluster

I have two mysql/galera clusters of three nodes each (two + garb node). The clusters are in separate DC's (dc1 and dc2) The cross cluster replication happens between node1-dc1 and node1-dc2 I want ...
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Ceph remain in HEALTH_WARN after osd remove

I have a cluster of 3 servers with cepth storage over 9 disks (3 each server). One osd is going down/out and so I "remove" it, after that system start to rebalance data over the remainig osd but after ...
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clvmd problems during the RHEV cluster deployment

We are deploying Red Hat Enterprise Virtualization cluster and we faced a problem attempting to start clvmd service after the lvm partition creating. The following has been completed successfully: ...
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Heavy write to Galera cluster - table locked, cluster practically unusable

I set up Galera Cluster on 3 nodes. It works perfectly for reading data. I have done simple application to make some test on the cluster. Unfortunately I have to say that the Cluster fails totally ...
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pcs status error httpd_monitor_5000 on server 'not running' (7):

Error Message Failed actions: httpd_monitor_5000 on abc-zabserver-b 'not running' (7): call=65, status=complete, last-rc-change='Wed Jul 15 21:44:43 2015', queued=0ms, exec=8ms pcs status ...
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364 views

Riak does not allow to add a node because it is in its own cluster

(this is a repost of my question from stack overflow, it was offtopic there, here is right place to ask it) I was trying to build a Riak cluster on Raspberry Pi. Created an image with Erland and ...
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246 views

RabbitMQ - How I do configure servers for zero-downtime upgrades?

Having read through the docs and RabbitMQ in Action, creating a RabbitMQ cluster seems straightforward enough, but upgrading or patching an existing RabbitMQ cluster seems to require the whole cluster ...
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Can we build a Hyper V failover cluster without a SAN or other shared storage?

I have a question about Hyper-V Failover Cluster. I have 2 server Hyper-V and want to use a failover cluster. As far as I know, I need a SAN server for that, so do we need it in here?
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14 views

Keepalived in the AWS autoscalling group

I want to deploy Keepalived in the AWS autoscalling group. The issue that Keepalived need to know ip address of the each node in the cluster, that is difficult in the elastic environment, where we ...
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1answer
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Cassandra 2.x - cluster does not rebalance after adding new nodes

I had 3 nodes, all with ~550GB, and added 4 more. I hoped that data would migrate on its own from old servers to new ones. Unfortunately after one day, data seems to stay in old places. In parallel, ...
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What “pieces” are needed in order to set up a cluster of physical servers?

Background: Currently, we use Rackspace cloud servers. We have no intention to stop using them, but would like to look into setting up a cluster of physical servers (probably desktop computers in the ...
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Is it a good idea to store Docker volumes in glusterfs?

I am currently thinking about migrating some of our servers and apps to a coreos enviroment. One of the problems I see here is the management of persistent data as coreos does not handle Docker ...
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1answer
44 views

MariaDB Galera Deployment

I am looking to experiment with MariaDB 10 Galera Cluster. I am looking for highly available, scalable and reliable architecture. Basically I am curious what would be the better architecture and would ...
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nginx automatic failover load balancing

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; ...
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1answer
1k views

Tomcat mod_jk cluster skip 404 http status

I am trying Tomcat Clustering with mod_jk for months and so far not so bad but facing a problem during deployment. I am using FarmDeployer to copy and deploy the WAR to other nodes in the cluster but ...
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33 views

Windows Cluster An error was encountered while determining shared storage

Our SAN manager has added a new disk for our cluster. this is a new 6TB disk that will be used for backup and will be part of a file share. I have put the disk online, initialized it and assigned the ...
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18 views

Galera cluster implementation questions

I've just successfully created my first Galera cluster using MariaDB 10.0.20 between three servers. I have a few questions regarding my implementation: 1. what will happen if one server becomes ...
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1answer
11 views

SQL alwaysON and WSFC

I have a WSFC configured on 2 (hardware)nodes with SQL AlwaysOn group. The problem is, if the node Where I have created the cluster goes down the cluster is not available for second node and here ...
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1answer
1k views

Apache Kafka consumer client connecting to Apache Zookeeper: EndOfStreamException

I get an error when trying to 'consume' messages from Kafka (2.9.2-0.8.1) with a Zookeer stand-alone (3.4.5). You can see the source code below as well as the error message and logfile from Zookeeper. ...
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Is it possible to create NUMA cluster containing 2-3x Dell / HP servers for SQL Server 2008 R2?

I want to create cluster of servers working at the same time on 1 query. Currently my server for some queries is providing unacceptable result time (server is providing data to the request for my ...
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2answers
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Why configure cluster nodes to reboot when out of memory?

I have access to a research HPC cluster which is configured so that if your job tries to use more memory than the node has available the node crashes and automatically reboots. This appears to be ...
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1answer
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What's the best way to manage product images in a Magento Cluster?

I'm running Magento CE on multiple web node. The Admin Backend is always running on the same server, so all the images are uploaded on this server. On my
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2answers
709 views

why would adding a crossover private nic cause IP address resource fail?

2 node Win 2008 R2 quorum cluster Configured 192.168.0.0/24 "public network" Configured cluster MSDTC Installed SQL 2008 R2 cluster instance Manually failover groups - OK Reboot server w/o failing ...
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34 views

What distributed FS, with small files read / write workload perform better?

I have 2 machines sharing storage via iscsi (multipath), soon we add another one, this machines are Web app servers that read small files on shared storage ( < 256kB), and write them back. so we ...
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1answer
18 views

SQL clustering without WSFC (Windows Server Failover Clustering)

Is it possible to cluster, or make SQL "highly available" without having to pay the huge enterprise prices? By the looks of it, any type of SQL clustering requires enterprise edition Windows Server. ...
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1answer
39 views

Can you list a Datastore Cluster's sDRS Schedule via PowerCLI?

We have a lot of datastore clusters, most if not all are supposed to have sDRS schedules applied to stop them moving VMs at busy periods. Obviously we could trawl through them manually to check if ...
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1answer
25 views

Multiple vCenter Services for redundancy

I've been reading up on linked mode, but this only applies to the management on multiple clusters from a single vCenter via linking other vCenter's into it. My question is - can you have two servers ...
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mysql galera 2-way cross-cluster replication

Scenario and setup Two mysql galera clusters in two datacenters with 2-way multi-master replication Each cluster has 3 nodes: 2 full nodes and 1 garbd node Example host names: dc1-sql1 --> ...
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242 views

Choice of distributed filesystem for intensive reads and writes

I have a series of servers (HP ProLiant, 34 servers) each of which with 500 G of hard drive space. These servers are part of a computational cluster which runs processes that roughly fall into two ...
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2answers
642 views

Clustering filesystem for small files

I'm looking for a distributed filesystem which I could use for storing lots of small files (<1MB usually). What I want to get is: 2 servers which have the fs mounted themselves and mirror the ...
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How does HA / failover work?

Let's say we have ten servers, each one has a copy of stateless application. user enters address in a browser / client program. dns server returns a list of ip (however many people say that dns ...
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1answer
17 views

Pacemaker and Stonith : passive node won't bring up resources

I'm working with Pacemaker and Stonith for High-Availability with a 2-node cluster (nodes called here A and B). Both nodes have one IPMI as fence device. The deal is : A is currently running ...
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Pacemaker ocf:heartbeat:IPaddr on different subnets

I'm trying to add a Pacemaker virtual IP address; with it, the gateway, and the two VMs it serves on different subnets. I've only done this before with all IPs on the same subnet, and I need some ...
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1answer
41 views

MariaDB Galera Cluster, Force Sync

I have three servers in a multi-master Galera cluster. I've imported some old databases recently, and noticed that the tables were being created across all three, but the data wasn't being ...
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1answer
17 views

How to manage access to nodes in a cluster?

I am about to set up a server cluster for our company's web applications. At the beginning there will be 3 hardware servers in Proxmox HA setup in a remote datacenter running about 20-30 VMs all ...
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1answer
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What happens if fleet can not meet the requirements for an unit

Take a look at the following scenario: I have a CoreOS / fleet cluster with 4 nodes. There are 4 apache units with the following line Conflicts=apache@%i.service One machine goes down. Fleet ...
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1answer
16 views

Cassandra NetworkTopologyStrategy

I would like to configure the following multi-datacenter Cassandra cluster: DC-EUROPE has 3 Cassandra nodes (1.1.1.1, 1.1.1.2, 1.1.1.3) DC-ASIA has 3 Cassandra nodes (2.2.2.1, 2.2.2.2, 2.2.2.3) Each ...
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7answers
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How to reserve complete nodes on Sun Grid Engine?

How do you use SGE to reserve complete nodes on a cluster? I don't want 2 processors from one machine, 3 processors from another, and so on. I have a quadcore cluster and I want to reserve 4 ...
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7answers
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alternative to Clusterssh for managing multiple SSH server

Is there any alternative to Clusterssh,pssh etc? to manage multiple ssh based servers through one interface? one weakness in Clusterssh is that my servers use key based authentication, with ...
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1answer
32 views

NetApp cluster fail to start

I have a big problem with my FAS2020 (configured as iScsi storage for 2 esxi 4 server). I couldn't ping the 2 ip address of the FAS so I connect by the serial port with putty for monitoring the boot ...
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LSF Cluster Upstart Job

So I would like machines in our office to auto start LSF on boot. So I took my first stab at writing an upstart job. The goal here is to run these commands for startup: /usr/local/lsf/bin/lsadmin ...
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How to mount disk in sheepdog cluster ?

In the documentation its given that, to mount the disk in the sheepdog node add following line in /etc/fstab /dev/sda1 /mnt/sheep/0 ext4 defaults,user_xattr,noatime 0 0 But I am facing some problem ...
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49 views

Heartbeat fails to start

I have two virtual machines running CentOS 6.6 (I use WMware workstation). I have heartbeat installed and configured on both. The configurations are: /etc/ha.d/ha.cf udpport 694 debugfile ...
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56 views

Why both nodes in OCFS2 cluster keep rebooting?

We created an OCSFS2 cluster by using SUSE Linux High Availability Extensions on SLES SP3. The cluster nodes are two Apache servers which share one disk. We have stonith enabled and SBD daemon. It ...
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21 views

How to use baseimage and deriverd image to create VMs in ceph cluster?

Scenerio: Suppose I have a template disk image and I want to use this to create many VMs by using this template file as a baseimage and derived image for different VM instances. in qemu we can use ...
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1answer
22 views

Pacemaker continously logging “Changed active directory”

I have a newly installed CentOS 6.6 two-node cluster using Pacemaker. Every 10 seconds /var/log/pacemaker.log shows this "Changed active directory to /var/lib/pacemaker/cores/root" message (and ...
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1answer
55 views

HA Cluster with OpenVZ and DRBD

I would like to create an HA Cluster using OpenVZ and DRBD. I found this tutorial http://www.olindata.com/blog/2013/12/building-ha-cluster-openvz-drbd-heartbeat-and-pacemaker and I got as far as Step ...
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1answer
202 views

Monitor network statistics with vnstat on CoreOS?

I notice that vnstat isn't installed on CoreOS. Is there a comparable way to monitor network usage on a CoreOS cluster? Certainly one could run vnstat through a Docker container but I assume that ...
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1answer
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zpool disappears whenever solaris cluster reboot or power cycle

I have following setup Oracle Solaris 10 -> 5.10 Generic_147147-26 sun4v sparc Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit production Oracle Solaris Cluster 3.3u2 for Solaris ...