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Gluster active/passive cluster

Gluster is a nice distributed file system which offers some management benefits over block level storage systems like DRBD. By design Gluster works in an active/active cluster configuration, however for applications where millisecond precision data replication is essential, an active/passive configuration is preferable. This is how (based on SLES11 with HAE): usual SLES HA cluster […]

Destroy gluster brick

If you wish to destroy or recreate a Gluster brick, it leaves some traces behind on the filesystem. This is the procedure to blat it: umount gluster volume stop gv0 gluster volume delete gv0 attr -lq /data/gv0/brick1 setfattr -x trusted.glusterfs.volume-id /data/gv0/brick1/ setfattr -x trusted.gfid /data/gv0/brick1/ rm –rf /data/gv0/brick1/.glusterfs /etc/init.d/glusterd restart

Server 2012 R2 – Failover Cluster error

So I was installing SQL2008R2 (In 2015? I know not my choice, it was for a legacy application) into a Windows Server 2012 R2 Failover Cluster. I hit the following error during the SQL install: “Rule Cluster Service Verification Failed. The SQL Server failover cluster services is not online”. It turns out that some cluster […]

Restart ESXi management agent

ESXi 5.x /etc/init.d/hostd restart /etc/init.d/vpxa restart ESXi 4.x /etc/init.d/hostd restart service vmware-vpxa restart ESX: service mgmt-vmware restart service vmware-vpxa restart

Linux open files limit

System-wide file descriptors limits: View: cat /proc/sys/fs/file-max Set: sysctl -w fs.file-max=100000 Set persistently: vi /etc/sysctl.conf fs.file-max = 100000 then run sysctl -p User level file descriptors limits: View: su – httpd $ ulimit -Hn $ ulimit -Sn Set: vi /etc/security/limits.conf httpd soft nofile 4096 httpd hard nofile 10240

Force dismount VMware tools

First post in two years, been incredibly busy and blogging always sinks to the bottom of the list! If VMware tools installer has been mounted to a VM for too long you may experience a scenario where you are unable to unmount it no matter how many times you click end or run dismount-tools. To […]

Load Balanced Linux Web Cluster

Another example of a load balanced apache cluster, this time active-active using Pacemaker/Corosync/ldirectord. This example is using CentOS. – fixed IP of server1 – fixed IP of server 2 – apache site 1 (virtual IP) – apache site 1 server 1 – apache site 1 server 2 – apache […]

Some Munin Notes

Munin – its pretty handy for monitoring stuff over time to view trends. Some notes to get it up and running with a minimal config: Install munin on monitoring server: apt-get install munin vi /etc/munin/munin.conf Add something like: [Webservers;webserver-01] address use_node_name yes [Webservers;webserver-01] address use_node_name yes Group by something sensible, i.e server type, […]

Some LVM Notes

A few LVM notes to jog the brain A. Steps to create the logical volume.. List the current physical volumes. In this instance, were interested in a blank 20GB SATA – /dev/sdb. You can extend a logical volume by adding additional phyical volumes later. fdisk -l Disk /dev/sda: 21.5 GB, 21474836480 bytes 255 heads, 63 […]

High Availability Linux Web Server Example

Just a quick example of setting up a Linux HA failover environment for an Apache/MySQL web server. This runs through a Ubuntu installation, however RedHat shouldn’t vary too much. – fixed IP of server1 – fixed IP of server2 – apache site1 (virtual IP) – apache site2 (virtual IP) Make sure […]