Some useful Linux commands

Check runlevel
$ who -r
Change runlevel
# vi /etc/inittab
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Format a SWAP partition:
# mkswap /dev/sda1
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iSCSI:
Discovering iSCSI Targets:
#iscsiadm -m discovery -t st -p <Group IP address>:3260
Logging in iSCSI Targets:
#iscsiadm -m node -l
#iscsiadm -m node -l -T <Complete Target Name> -p <Group IP>:3260
Example:
#iscsiadm -m node -l -T iqn.2001-05.com.equallogic:83bcb3401-16e0002fd0a46f3d-rhel5-test -p 172.23.10.240:3260
Logging out iSCSI Targets:
#iscsiadm -m node -u
#iscsiadm -m node -u -T <Complete Target Name> -p <Group IP address>:3260
Example:
#iscsiadm -m node -u -T iqn.2001-05.com.equallogic:83bcb3401-16e0002fd0a46f3d-rhel5-test -p 172.23.10.240:3260

Restart iSCSI service:
# /etc/init.d/iscsi restart
Delete old target:
iscsiadm -m node -p 192.198.1.148 --op=delete

Check connected target:
/var/lib/iscsi/nodes/
Server IQN:
# cat /etc/iscsi/initiatorname.iscsi
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測試iSCSI target在Linux上的I/O速度。
# hdparm -tT /dev/sdb1
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Network:
# vi /etc/sysconfig/network
GATEWAY=your-ip
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0:0
IPADDR=192.168.1.7
NETMASK=255.255.255.0
NETWORK=192.168.1.0
ONBOOT=yes
NAME=eth0:0
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YUM Local Repo:
# vi /etc/yum.repos.d/rhel-debuginfo.repo
[cdrom]
name=RHEL $releasever-$basearch CDROM
baseurl=file:///media/cdrom/Server
enabled=1
gpgchechk=1
gpgkey=file:///media/cdrom/RPM-GPG-KEY-redhat-release
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