转：iSCSI Target & Initiator in RHEL 5.3

简介：
RHEL 5.3 开始，提供了编译好的 iscsi target 。
这里转载一篇相关的文章，原文由两个部分组成，分别介绍 target 和 Initiator， 这里将两篇合二为一。

Orignal Site: http://pbraun.nethence.com 

iSCSI targets

Introduction

The target name may be forged like e.g.,

iqn.2010-07.net.example:disk50gb

Note. lowcase characters only, otherwise some initiators won't accept it (namely Microsoft iSCSI initiator).

TGT iSCSI target (since RHEL 5.3)

Install TGT,

yum install scsi-target-utils

Make sure you've got a LV or an disk to share,

fdisk -l

Start and enable the daemon at boot time,

/etc/init.d/tgtd start

chkconfig tgtd on

create the target and define its name,

tgtadm --lld iscsi --mode target --op new --tid=1 --targetname iqn.2010-07.net.example:disk50gb

note. id must not be zero

add a LUN to the target,

tgtadm --lld iscsi --mode logicalunit --op new --tid=1 --lun=1 --backing-store=/dev/sdb

note. lun >=1

note. it's also possible to use a vdisk file instead of /dev/sdb

enable the target to accept any initiators,

tgtadm --lld iscsi --mode target --op bind --tid=1 -I ALL

check port 3260,

netstat -apne | grep 3260

#lsof -i:3260

Note. to check for targets, luns, and connected initiators,

tgtadm --lld iscsi --mode target --op show

Note. to delete a LUN,

tgtadm --lld iscsi --mode logicalunit --op delete --tid=1 --lun=1

Note. to delete a target,

tgtadm --lld iscsi --mode target --op delete --tid=1

IET iSCSI target

Get IET (iscsitarget.sourceforge.net/) and install it from source,

yum install kernel-devel openssl-devel gcc

wget freefr.dl.sourceforge.net/sourceforge/iscsitarget/iscsitarget-0.4.17.tar.gz

tar xvzf iscsitarget-0.4.17.tar.gz

cd iscsitarget-0.4.17

make

make install

Make sure you've got a LV or an disk to share,

fdisk -l

Configure the LUNs,

vi /etc/ietd.conf

like,

Target iqn.2009-05.net.example:vdisk20gb

Lun 0 Path=/dev/sdb,Type=blockio

MaxConnections 2

InitialR2T No

ImmediateData Yes

Note. MaxConnections' default is 1...

Note. "/dev/sdb" here

Note. "vdisk20gb" as an example here, needs to be a unique string.

Authorize all clients,

vi /etc/initiators.allow

like,

iqn.2009-05.net.example:vdisk20gb ALL

Launch the daemon and activate on boot,

service iscsi-target start

chkconfig iscsi-target on

Check the service is running,

ps aux | grep ietd

Check for exported LUNs,

cat /proc/net/iet/volume

NetBSD iSCSI target

As an alternative, there's also NetBSD's iSCSI target software.

Get the RPM from EPEL (fedoraproject.org/wiki/EPEL) and install it,

rpm -ivh netbsd-iscsi-20071205-1.el5.i386.rpm

Check how much bytes you have to export,

fdisk -l /dev/sdb

Substract one byte to define the export length thereafter.

Configure the target,

vi /etc/iscsi/targets

like,

## extent file or device start length

extent0 /dev/sdb 0 62277025791

# target flags storage netmask

target0 rw extent0 10.1.1.0/24

Start the daemon,

/usr/sbin/iscsi-target

References

Linux SCSI target framework (tgt) project : stgt.berlios.de/

tgtadm(8) - Linux man page : linux.die.net/man/8/tgtadm

The iSCSI Enterprise Target Project : iscsitarget.sourceforge.net/

The NetBSD iSCSI HOWTO : ftp.netbsd.org/pub/NetBSD/misc/agc/HOWTO-iSCSI-target.txt

How to setup an iSCSI target using tgtadm in Red Hat Enterprise Linux 5 : kbase.redhat.com/faq/docs/DOC-15154

Linux tgtadm: Setup iSCSI Target ( SAN ) : www.cyberciti.biz/tips/howto-setup-linux-iscsi-target-sanwith-tgt.html

iSCSI target HowTo on Enterprise Linux (RHEL4) : mail.digicola.com/wiki/index.php?title=User:Martin:iSCSI

Linux iscsitarget+tools : www3.amherst.edu/~swplotner/iscsitarget/

Additional references

en.wikipedia.org/wiki/ATA_over_Ethernet

en.wikipedia.org/wiki/Fibre_Channel_over_Ethernet

iSCSI initiators

Introduction

If using an STGT on the target side, you will see a weired LUN0 on the initiator. Just discard it and on Windows, just don't configure any driver for it (lists.wpkg.org/pipermail/stgt/2009-February/002633.html).

RHEL4/5 configuration

Install the iscsi initiator RPM,

yum install iscsi-initiator-utils

Note. although the package name is identical on RHEL4/5, it's different :

- configuration file and paths

- rhel5 has 'iscsi' and 'iscsid' init scripts

- rhel4 only has 'iscsi' init script

RHEL5

On RHEL5,

cd /etc/iscsi

mv iscsid.conf iscsid.conf.dist

sed -e '

/^[[:space:]]*$/d;

/^[[:space:]]*#/d;

' iscsid.conf.dist > iscsid.conf

Note. the default config is fine for dedicated VLANs but if you need CHAP authentication add,

node.session.auth.authmethod = CHAP

node.session.auth.username = USERNAME

node.session.auth.password = PASSWORD

discovery.sendtargets.auth.authmethod = CHAP

discovery.sendtargets.auth.username = USERNAME

discovery.sendtargets.auth.password = PASSWORD

Enable the iscsi daemon,

service iscsid start

chkconfig iscsid on

Note. we'll activate /etc/init.d/iscsi (to log into targets automaticly) later on

RHEL4

On RHEL4,

cd /etc

mv iscsi.conf iscsi.conf.dist

vi iscsi.conf

like,

DiscoveryAddress=ISCSI_SERVER

# OutgoingUserName=USERNAME

# OutgoingPassword=PASSWORD

LoginTimeout=15

ref. www.cyberciti.biz/tips/howto-centos-rhel4-iscsi-initiators.html

fix the perm,

chmod 600 iscsi.conf

Enable the iscsi daemon,

service iscsi start

chkconfig iscsi on

RHEL4/5 finish up

Check the iSCSI target is available on the network,

telnet ISCSI_TARGET 3260

Discover and login to all available targets,

iscsiadm -m discovery -t st -p ISCSI_TARGET

Note. for a specific interface e.g. 'bond0' for trunking, add '-I bond0'

Note. eventually add "-d" to the iscsiadm command for debugging

Note. login to a precise LUN,

iscsiadm -m node -L automatic

#iscsiadm -m node -T iqn.2010-07.net.example:disk50gb -p ISCSI_TARGET

Show current records and sessions,

iscsiadm -m node

iscsiadm -m session

Ready to go ! Check for new disks,

cat /proc/scsi/scsi

fdisk -l

Note. to logout all sessions,

iscsiadm -m node -U all

Log again to the target but with the init script, and enable it for boot time,

service iscsi start

chkconfig iscsi on

Note. don't restart that daemon ! It would change the device name until next reboot (for example, sdc would become sdd instantly...)

RHEL4/5 troubbleshooting

If you experience this error when shutting down the system,

Synchronizing SCSI cache for disk sdb

it's simply becuase the iscsi disk hasn't been removed. Enable the iscsi (beside iscsid) daemon to unlog from the target before completely shutting down the system.

Microsoft iSCSI Software Initiator

Discover the target,

Discovery tab > Add

then

IP address or DNS name : ...

proceed,

Targets tab > select a target > Log On...

To log off,

Targets tab > select a target > Details

then,

Sessions tab > check a target > Log off...

and unconfigure a target,

Discovery tab > select a target portal > Remove

StarWind Software Starport

Instead of "Microsoft iSCSI Software Initiator" (www.microsoft.com/downloads/) you may use StarWind Software's one : StarPort (www.starwindsoftware.com/starport-free).

Get StarPort and the Personal Free License .spk file. Install it and put the .spk file inside the installation directory,

C:\Program Files\StarWind Software\StarPort

note. the program won't start if the .spk file isn't there.

start the program and register with that licence,

Help > Register Startport...

then in the Registration window,

Load from file > C:\Program Files\StarWind Software\StarPort\StarPort_Free_Personal_License_1978.spk

click "Register"

Add a iSCSI disk,

right click on "Remote iSCSI devices" > Add device

then into the Wizard,

Remote iSCSI device IP Address or Machine Name : ISCSI_SERVER

Remote iSCSI device Port number : 3260

select a target

keep "Automount this device" box checked

To log off,

right click on an iSCSI disk > Remove device

References

www.microsoft.com/downloads/

www.microsoft.com/windowsserver2003/technologies/storage/iscsi/default.mspx

ISCSI and XEN Server Storage Repository issue : forums.openfiler.com/viewtopic.php?id=2280

ISCSI : www.gentoo-wiki.info/ISCSI