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# Tested on RHEL 7
# iSCSI target configuration # ------------------------------------------------------------------------------------------ # Install required package: targetcli yum install -y targetcli # and enable the target service on startup systemctl enable target # To create an iSCSI target, we'll use 'targetcli', tool for administering targets: targetcli targetcli shell version 2.1.fb41 Copyright 2011-2013 by Datera, Inc and others. For help on commands, type 'help'. /> # As backstore, the exported SCSI device, we may choose between "fileio", a file treated # as a disk image, "block", a local disk block device such as a LVM logical volume or a # physical device (HDD, DVD, etc), "pscsi" , a local SCSI device of any type, and "ramdisk", # shared kernel memory. For test purposes, we could also use "nullio" mode, which is not # backed by any storage and discards all writes, and returns all-zeroes for reads. # To simplify things, I'll use a fileio device. # Fileio storage can support either 'write_back' or 'write_thru' operation. The 'write_back' # enables the local file system cache. This improves performance but increases the risk of # data loss. It is recommended to use 'write_back=false' to disable 'write_back' in favor # of 'write_thru'. # I'll create my fileio backstore, "sharedLUN", of 512M. /> /backstores/fileio/ create sharedLUN /myluns/sharedLUN.img 512M write_back=false Created fileio sharedLUN with size 536870912 # To create a block backstore, use a command like following one: # /> /backstores/block create name=block_backend dev=[/dev/sdc|/dev/iscsivg/lv_iscsi] # Note that block backstores usually provide the best performance. # Then, I create an IQN (Iscsi Qualified Name) called iqn.2016-02.com.example.myserver with # a target named "myiscsi" and get an associated TPG (Target Portal Group): /> /iscsi/ create iqn.2016-02.com.example.myserver:myiscsi Created target iqn.2016-02.com.example.myserver:myiscsi. Created TPG 1. Global pref auto_add_default_portal=true Created default portal listening on all IPs (0.0.0.0), port 3260. /> cd /iscsi/iqn.2016-02.com.example.myserver:myiscsi/tpg1 /iscsi/iqn.20...:myiscsi/tpg1> ls o- tpg1 ..................................................... [no-gen-acls, no-auth] o- acls ................................................................ [ACLs: 0] o- luns ................................................................ [LUNs: 0] o- portals .......................................................... [Portals: 0] # Depending on the RHEL 7 version it may be that a default portal is automatically created # by the "/iscsi/ create" command. If it is not the case, let's create one. For that we # have two options: create a default portal, or create a portal specifying what IP address # to listen to. Creating a default portal uses the default iSCSI port 3260 and allows the # target to listen on all IP addresses on that port. # I'll create a default portal /iscsi/iqn.20...:myiscsi/tpg1> portals/ create Using default IP port 3260 Binding to INADDR_ANY (0.0.0.0) Created network portal 0.0.0.0:3260 # Otherwise, to create a portal specifying what IP address to listen to, use this: # /iscsi/iqn.20...:myiscsi/tpg1> portals/ create 192.168.54.113 # Using default IP port 3260 # Created network portal 192.168.54.113:3260 # Now, create a lun. Depending on the kind of backstore previously chosen: /iscsi/iqn.20...:myiscsi/tpg1> luns/ create /backstores/fileio/sharedLUN Created LUN 0. # For the block backstore shown here above # /iscsi/iqn.20...:myiscsi/tpg1> luns/ create /backstores/block/block_backend # Finally, create an acl and an identifier /iscsi/iqn.20...:myiscsi/tpg1> acls/ create iqn.2016-02.com.example.myserver:client Created Node ACL for iqn.2016-02.com.example.myserver:client Created mapped LUN 0. /iscsi/iqn.20...:myiscsi/tpg1> cd acls/iqn.2016-02.com.example.myserver:client/ /iscsi/iqn.20...server:client> set auth userid=myuser Parameter userid is now 'myuser'. /iscsi/iqn.20...server:client> set auth password=mypassword Parameter password is now 'mypassword'. /iscsi/iqn.20...server:client> cd ../.. /iscsi/iqn.20...:myiscsi/tpg1> ls o- tpg1 ................................................................... [no-gen-acls, no-auth] o- acls .............................................................................. [ACLs: 1] | o- iqn.2016-02.com.example.myserver:client .................................. [Mapped LUNs: 1] | o- mapped_lun0 ................................................ [lun0 fileio/sharedLUN (rw)] o- luns .............................................................................. [LUNs: 1] | o- lun0 ........................................... [fileio/sharedLUN (/myluns/sharedLUN.img)] o- portals ........................................................................ [Portals: 1] o- 0.0.0.0:3260 ......................................................................... [OK] # We're done. On exit is automatically saved to /etc/target/saveconfig.json file /iscsi/iqn.20...:myiscsi/tpg1> exit Global pref auto_save_on_exit=true Last 10 configs saved in /etc/target/backup. Configuration saved to /etc/target/saveconfig.json # Out iSCSI target is ready to be used. # If you ever want to clean the entire current local configuration, you can do it by running # targetcli command like this: # targetcli clearconfig confirm=true All configuration cleared # iSCSI initiator configuration # ------------------------------------------------------------------------------------------ # Install required package: iscsi-initiator-utils yum install -y iscsi-initiator-utils # Edit /etc/iscsi/initiatorname.iscsi file and replace default content with the initiator # name configured as acl on target side: vi /etc/iscsi/initiatorname.iscsi InitiatorName=iqn.2016-02.com.example.myserver:client # If userid and a password have been configured on the server, edit /etc/iscsi/iscsid.conf # and uncomment/modify following lines vi /etc/iscsi/iscsid.conf node.session.auth.authmethod = CHAP node.session.auth.username = myuser node.session.auth.password = mypassword # In RHEL 7, the iSCSI service is lazily started by default. That is, should an iscsiadm # command be issued the service will start. # Discover the target iscsiadm --mode discovery --type sendtargets --portal 192.168.54.113 192.168.54.113:3260,1 iqn.2016-02.com.example.myserver:myiscsi # Log in to the target iscsiadm --mode node --targetname iqn.2016-02.com.example.myserver:myiscsi --portal 192.168.54.113 --login Logging in to [iface: default, target: iqn.2016-02.com.example.myserver:myiscsi, portal: 192.168.54.113,3260] (multiple) Login to [iface: default, target: iqn.2016-02.com.example.myserver:myiscsi, portal: 192.168.54.113,3260] successful. # Check the newly discovered target lsblk --scsi NAME HCTL TYPE VENDOR MODEL REV TRAN sda 1:0:0:0 disk ATA ST3160815A D ata sdb 1:0:1:0 disk ATA ST3160021A 8.01 ata sdc 3:0:0:0 disk ATA ST3160215ACE G ata sdd 8:0:0:0 disk LIO-ORG sharedLUN 4.0 iscsi sr0 3:0:1:0 rom HL-DT-ST DVDRAM GSA-4120B A102 ata lsblk | egrep "NAME|sdd" NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sdd 8:48 0 512M 0 disk # Now we are ready to start working with the target. For instance: mkfs.ext4 /dev/sdd [...] blkid /dev/sdd /dev/sdd: UUID="35968eb6-b024-485b-a859-71475285c39b" TYPE="ext4" # If you are planning to persistently mount target, add a line like this to /etc/fstab: UUID=35968eb6-b024-485b-a859-71475285c39b /mnt ext4 _netdev 0 0 # Display initiator configuration iscsiadm -m session -P 3 iSCSI Transport Class version 2.0-870 version 6.2.0.873-30 Target: iqn.2016-02.com.example.myserver:myiscsi (non-flash) Current Portal: 192.168.54.113:3260,1 Persistent Portal: 192.168.54.113:3260,1 ********** Interface: ********** Iface Name: default Iface Transport: tcp Iface Initiatorname: iqn.2016-02.com.example.myserver:client Iface IPaddress: 192.168.54.113 Iface HWaddress: <empty> Iface Netdev: <empty> SID: 1 iSCSI Connection State: LOGGED IN iSCSI Session State: LOGGED_IN Internal iscsid Session State: NO CHANGE ********* Timeouts: ********* Recovery Timeout: 120 Target Reset Timeout: 30 LUN Reset Timeout: 30 Abort Timeout: 15 ***** CHAP: ***** username: myuser password: ******** username_in: <empty> password_in: ******** ************************ Negotiated iSCSI params: ************************ HeaderDigest: None DataDigest: None MaxRecvDataSegmentLength: 262144 MaxXmitDataSegmentLength: 262144 FirstBurstLength: 65536 MaxBurstLength: 262144 ImmediateData: Yes InitialR2T: Yes MaxOutstandingR2T: 1 ************************ Attached SCSI devices: ************************ Host Number: 8 State: running scsi8 Channel 00 Id 0 Lun: 0 Attached scsi disk sdd State: running |