8.5. Riconfigurare Pacemaker per l'Active/Active
Quasi tutto è a posto. Le versioni recenti di DRBD supportano l'operare in modalità Primary/Primary ed inoltre il filesystem utilizzato è cluster aware. Tutto ciò che rimane da fare è configurare nuovamente il cluster per sfruttare queste peculiarità.
Questo richiederà diversi cambiamenti, pertanto verrà utilizzata ancora una volta la modalità interattiva.
# crm # cib new active
There’s no point making the services active on both locations if we can’t reach them, so lets first clone the IP address. Cloned IPaddr2 resources use an iptables rule to ensure that each request only gets processed by one of the two clone instances. The additional meta options tell the cluster how many instances of the clone we want (one "request bucket" for each node) and that if all other nodes fail, then the remaining node should hold all of them. Otherwise the requests would be simply discarded.
meta globally-unique="true" clone-max="2" clone-node-max="2"
Ora bisogna indicare a ClusterIP come decidere quali richieste sono processate e da quali host. Per fare ciò è necessario definire il parametro clusterip_hash.
Aprire la risorsa ClusterIP
ed aggiungere il seguente testo alla linea dei parametri
clusterip_hash="sourceip"
In modo che la definizione completa sia simile alla seguente:
primitive ClusterIP ocf:heartbeat:IPaddr2 \
params ip="192.168.122.101" cidr_netmask="32" clusterip_hash="sourceip" \
op monitor interval="30s"
Questa è la trascrizione completa
INFO: active shadow CIB created
crm(active)
meta globally-unique="true" clone-max="2" clone-node-max="2"
crm(active)
node pcmk-2
primitive WebData ocf:linbit:drbd \
params drbd_resource="wwwdata" \
op monitor interval="60s"
primitive WebFS ocf:heartbeat:Filesystem \
params device="/dev/drbd/by-res/wwwdata" directory="/var/www/html" fstype="gfs2"
primitive WebSite ocf:heartbeat:apache \
params configfile="/etc/httpd/conf/httpd.conf" \
op monitor interval="1min"
primitive ClusterIP ocf:heartbeat:IPaddr2 \
params ip="192.168.122.101" cidr_netmask="32" clusterip_hash="sourceip" \
op monitor interval="30s"
ms WebDataClone WebData \
meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"
clone WebIP ClusterIP \
meta globally-unique="true" clone-max="2" clone-node-max="2"
colocation WebSite-with-WebFS inf: WebSite WebFS
colocation fs_on_drbd inf: WebFS WebDataClone:Master
colocation website-with-ip inf: WebSite WebIPorder WebFS-after-WebData inf: WebDataClone:promote WebFS:start
order WebSite-after-WebFS inf: WebFS WebSiteorder apache-after-ip inf: WebIP WebSite
property $id="cib-bootstrap-options" \
dc-version="1.1.5-bdd89e69ba545404d02445be1f3d72e6a203ba2f" \
cluster-infrastructure="openais" \
expected-quorum-votes="2" \
stonith-enabled="false" \
no-quorum-policy="ignore"
rsc_defaults $id="rsc-options" \
resource-stickiness="100"
Notare come qualsiasi constraint riferita a ClusterIP sia stata aggiornata per utilizzare invece WebIP. Questo è un vantaggio aggiuntivo nell'utilizzo della shell crm.
A questo punto è necessario convertire le risorse filesystem ed Apache in cloni. Di nuovo, la shell aggiornerà automaticamente ogni constraint interessata.
crm(active)
crm(active)
L'ultimo passo è quello di comunicare al cluster che ora è consentito promuovere entrambe le istanze a PRimary (o Master).
crm(active)
Cambiare master-max a 2
crm(active)
node pcmk-1
node pcmk-2
primitive WebData ocf:linbit:drbd \
params drbd_resource="wwwdata" \
op monitor interval="60s"
primitive WebFS ocf:heartbeat:Filesystem \
params device="/dev/drbd/by-res/wwwdata" directory="/var/www/html" fstype="gfs2"
primitive WebSite ocf:heartbeat:apache \
params configfile="/etc/httpd/conf/httpd.conf" \
op monitor interval="1min"
primitive ClusterIP ocf:heartbeat:IPaddr2 \
params ip="192.168.122.101" cidr_netmask="32" clusterip_hash="sourceip" \
op monitor interval="30s"
ms WebDataClone WebData \
meta master-max="2" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"
clone WebFSClone WebFSclone WebIP ClusterIP \
meta globally-unique="true" clone-max="2" clone-node-max="2"
clone WebSiteClone WebSitecolocation WebSite-with-WebFS inf: WebSiteClone WebFSClone
colocation fs_on_drbd inf: WebFSClone WebDataClone:Master
colocation website-with-ip inf: WebSiteClone WebIP
order WebFS-after-WebData inf: WebDataClone:promote WebFSClone:start
order WebSite-after-WebFS inf: WebFSClone WebSiteClone
order apache-after-ip inf: WebIP WebSiteClone
property $id="cib-bootstrap-options" \
dc-version="1.1.5-bdd89e69ba545404d02445be1f3d72e6a203ba2f" \
cluster-infrastructure="openais" \
expected-quorum-votes="2" \
stonith-enabled="false" \
no-quorum-policy="ignore"
rsc_defaults $id="rsc-options" \
resource-stickiness="100"
Prima di caricare la configurazione nel cluster questa va revisionata, la shell andrà terminata e si dovrà osservare il responso del cluster
crm(active)
INFO: commited 'active' shadow CIB to the cluster
crm(active)
bye
============
Last updated: Thu Sep 3 21:37:27 2009
Stack: openais
Current DC: pcmk-2 - partition with quorum
Version: 1.1.5-bdd89e69ba545404d02445be1f3d72e6a203ba2f
2 Nodes configured, 2 expected votes
6 Resources configured.
============
Online: [ pcmk-1 pcmk-2 ]
Master/Slave Set: WebDataClone
Masters: [ pcmk-1 pcmk-2 ]
Clone Set: WebIP Started: [ pcmk-1 pcmk-2 ]
Clone Set: WebFSClone Started: [ pcmk-1 pcmk-2 ]
Clone Set: WebSiteClone Started: [ pcmk-1 pcmk-2 ]
8.5.1. Testare il recovery
TODO: mettere un nodo in standby per dimostrare il failover