ActiveMQ Master/Slave KahaDB on OCFS2 shared file system
During my tests of shared storage clusters I wondered if ActiveMQ supports file locking on OCFS2 file system which I used on couple of occasions. While looking into it I came across the following warning on the Apache project site:…
Highly Available iSCSI ALUA (Asymetric Logical Unit Access) Storage with Pacemaker and DRBD in Dual-Primary mode – Part2
This is continuation of the Highly Available iSCSI ALUA Storage with Pacemaker and DRBD in Dual-Primary mode series. We have setup the HA backing iSCSI storage and now we are going to setup a HA shared storage on the client…
Highly Available iSCSI ALUA (Asymetric Logical Unit Access) Storage with Pacemaker and DRBD in Dual-Primary mode – Part1
I already wrote a post on this topic so this is kind of extension or variation of the setup described here Highly Available iSCSI Storage with SCST, Pacemaker, DRBD and OCFS2. The main and most important difference is that thanks…
Highly Available iSCSI Storage with SCST, Pacemaker, DRBD and OCFS2 – Part2
This is continuation of the Highly Available iSCSI Storage with SCST, Pacemaker, DRBD and OCFS2 series. We have setup the HA backing iSCSI storage and now we are going to setup a HA shared storage on the client side. iSCSI…
Highly Available iSCSI Storage with SCST, Pacemaker, DRBD and OCFS2 – Part1
SCST the generic SCSI target subsystem for Linux, allows creation of sophisticated storage devices from any Linux box. Those devices can provide advanced functionality, like replication, thin provisioning, deduplication, high availability, automatic backup, etc. SCST devices can use any link…
GlusterFS metadata split brain recovery
While investigating an error related to failed documents I came across following error in the GlusterFS healing daemon log file: [2015-11-08 23:22:38.700539] E [afr-self-heal-common.c:197:afr_sh_print_split_brain_log] 0-gfs-volume-vol1-replicate-0: Unable to self-heal contents of ” (possible split-brain). Please delete the file from all but…
GlusterFS internals
GlusterFS stores metadata info in extended attributes which is supported and enabled by default in the XFS file system we use for the bricks. This is different approach then some other distributed storage cluster systems like Ceph for example that…
HAProxy dynamically adjust server weight using external agent
Trying to utilize HAProxy-1.5/1.6 agent-check feature, see HAProxy documentation, I wrote this small script to check Tomcat system load and return back some values that HAP can use to dynamically adjust the server weight in the backend. This will run…
HAProxy OCSP stapling
The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate. It is used by https clients (browsers) to confirm that the certificate sent by the server they have connected…
Securing Logstash to Redis communication with Stunnel
Logstash is meant for private LAN usage since it doesn’t offer any kind of encryption support. If we need to ship sensitive data across WAN’s, like between Amazon VPC’s, we would like to have the communication channel secure. That’s where…