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# pvcreate /dev/sda
# pvcreate /dev/sdb
# pvcreate /dev/sdc
# vgcreate my_volume_group /dev/sda /dev/sdb /dev/sdc
# vgdisplay
# lvcreate -i3 -I4 -L1G -nmy_logical_volume my_volume_group
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Web frontend for cluster (when xen cluster kernel)
yum install luci ricci
luci_admin init
service luci restart
GTK+ tool for cluster configuration (/etc/cluster/cluster.conf)
yum install system-config-cluster
system-config-cluster
Resource Group Manager
yum install cman rgmanager
rpm -qil cman | grep ccsd
Global Filesystem
yum list \*gfs\*
yum install gfs2-utils kmod-gfs2-xen
mkfs.gfs2 -j 2 -p lock_dlm -t new_cluster:gfs /dev/sdb1
Cluster monitor
service cman start
clusvcadm status
clusvcadm -l
cman status
cman_tool status
clustat
service dlm status
cman_tool nodes
Cluster config XML
<?xml version="1.0" ?>
<cluster config_version="3" name="new_cluster">
<fence_daemon post_fail_delay="0" post_join_delay="3"/>
<clusternodes>
<clusternode name="172.16.50.15" nodeid="1" votes="1">
<fence/>
</clusternode>
<clusternode name="172.16.50.25" nodeid="2" votes="1">
<fence/>
</clusternode>
</clusternodes>
<cman expected_votes="1" two_node="1"/>
<fencedevices>
<fencedevice agent="fence_manual" name="cloveck"/>
</fencedevices>
<rm>
<failoverdomains/>
<resources/>
<vm autostart="1" name="node1" path="/etc/xen/node1"/>
<vm autostart="1" name="node2" path="/etc/xen/node2"/>
</rm>
</cluster>
Cluster reference (RH)
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To backup all the mails user1@domain.tld for specific sender: edit /etc/postfix/main.cf and add:
sender_bcc_maps = hash:/etc/postfix/sender_bcc
Then edit or create /etc/postfix/sender_bcc in the following format:
user1@domain.tld copy@domain.tld
and run postmap /etc/postfix/sender_bcc and posfix reload. The same is if backing up recipient's mail.
recipient_bcc_maps = hash:/etc/postfix/recipient_bcc
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sdparm RPM packages for Red Hat, CentOS and Fedora
To list common mode parameters of a disk, enter:
# sdparm /dev/sda
To list the designators within the device identification VPD page of a disk:
# sdparm --inquiry /dev/sdb
To see all parameters for the caching mode page:
# sdparm --page=ca /dev/sdc
To set the "Writeback Cache Enable" bit in the current values page:
# sdparm --set=WCE /dev/sda
taken: http://www.cyberciti.biz/tips/sdparm-li ... ibute.html
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Afterwards we must install the GRUB bootloader on the second hard drive /dev/sdb:
grub
On the GRUB shell, type in the following commands:
root (hd0,0)
grub> root (hd0,0)
Filesystem type is ext2fs, partition type 0x83
grub>
setup (hd0)
grub> setup (hd0)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"... 15 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/grub/stage2 /grub/menu.lst"... succeeded
Done.
grub>
root (hd1,0)
grub> root (hd1,0)
Filesystem type is ext2fs, partition type 0xfd
grub>
setup (hd1)
grub> setup (hd1)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd1)"... 15 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd1) (hd1)1+15 p (hd1,0)/grub/stage2 /grub/menu.lst"... succeeded
Done.
grub>
quit
taken: http://www.howtoforge.com/software-raid ... an-etch-p2
Grub got deleted:
find /boot/grub/stage1 (optional)
root (hdX,Y)
setup (hd0)
quit http://www.dedoimedo.com/computers/grub ... ocId976410
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Copy partition layout from a disk to file somewhere:
sfdisk -d /dev/sda > /raidinfo/partitions.sda
Mark all the parts on the disk which will be replaced as failed:
mdadm --manage /dev/md0 --fail /dev/sdb1
Then remove all the related partitions from the raid:
mdadm --manage /dev/md0 --remove /dev/sdb1
Power down system:
shutdown -h now
After hard disk is swapped, boot the system and create the same partitioning on a new disk.
sfdisk /dev/sda < /raidinfo/partitions.sda
Then add /dev/sdb1 to /dev/md0 and other partitions as well:
mdadm --manage /dev/md0 --add /dev/sdb1
Next, install Grub boot loader on replaced disk.
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#!/bin/bash
DOMU=$1
XM_CMD="/usr/sbin/xm"
sudo $XM_CMD list | grep $DOMU 1>/dev/null
if [ $? -ne 0 ]; then
echo "CRITICAL: The domU $DOMU seems to be down!"
exit 2
else
TIME=`sudo $XM_CMD list | grep $DOMU | awk '{ print $6 }'`
VCPU=`sudo $XM_CMD list | grep $DOMU | awk '{print $4}'`
MEM=`sudo $XM_CMD list | grep $DOMU | awk '{print $3}'`
STATE=`sudo $XM_CMD list | grep $DOMU | awk '{print $5}' | sed 's/-//g'`
if [ $STATE == "d" ]; then
echo "WARNING: $DOMU seems to be dying (Time=$TIME) (MEM=$MEM) (VCPU=$VCPU) (STATE=$STATE)";
exit 2;
elif [ $STATE == "p" ]; then
echo "WARNING: $DOMU seems to be paused (Time=$TIME) (MEM=$MEM) (VCPU=$VCPU) (STATE=$STATE)";
exit 1;
elif [ $STATE == "c" ]; then
echo "CRITICAL: $DOMU seems to be crashed (Time=$TIME) (MEM=$MEM) (VCPU=$VCPU) (STATE=$STATE)";
exit 2;
else echo "OK: $DOMU seems to be up (Time=$TIME) (MEM=$MEM) (VCPU=$VCPU) (STATE=$STATE)"
fi
exit 0
fi
done
the check above is running under the nagios nrpe as nagios user. therefore we need to allow nagios user to execute xm commands.
# #Defaults requiretty <-- disable this!
### XEN
Cmnd_Alias XEN = /usr/sbin/xm
## Allows members of the users group to shutdown this system
# %users localhost=/sbin/shutdown -h now
%nagios ALL = NOPASSWD: XEN
There is no need for disabling requiretty globally:
Defaults requiretty
Much safer and tighter is to disable requiretty only for the user nagios runs as:
Defaults:nagios !requiretty
e
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Environmental and Health Concerns
Associated with Compact Fluorescent Lights
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