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  6. Configuring iSCSI (Cross-AZ HA Deployment)

Configuring iSCSI (Cross-AZ HA Deployment)

Scenarios

This operation is required only in the cross-AZ HA scenario.

EVS disks cannot be shared across AZs. Therefore, three ECSs are required in the cross-AZ HA scenario. Each ECS is bound to a SCSI disk and iSCSI configuration is required for SBD. Table 1 lists the ECS specifications.

If an SAP NetWeaver system is deployed across three AZs, create an ECS in each AZ. If an SAP NetWeaver system is deployed across two AZs, create an ECS in an AZ and two ECSs in the other AZ. The three ECSs must belong to the same ECS group.

Table 1 ECS specifications

OS

SUSE Linux Enterprise Server 12 SP1

Flavor

s1.medium (1 vCPU and 4 GB memory)

Disk

System disk: common I/O

Data disk: Common I/O, 10 GB, SCSI, non-shared disk

Prerequisites

You have created three ECSs.

Procedure

Software installation

NOTE:

Before installing the software, update the software source. Run the following command to update the software source:

zypper ar --refresh Software source network address

  1. Run the following command to install open-iscsi on the server side (three ECSs):

    zypper in open-iscsi yast2-iscsi-lio-server targetcli

  2. Run the following command to install open-iscsi on the client side (SAP HANA node):

    zypper in open-iscsi

Server side configuration

  1. Log in to a server side ECS.
  1. Run the following commands to configure automatic service startup:

    systemctl enable targetcli

    systemctl enable target

  2. Run the following command to use the /dev/sda disk to create an Iblock device named stonith_bd:

    targetcli /backstores/iblock create stonith_bd /dev/sda

    NOTE:

    /dev/sda is the drive letter of the data disk. Set it based on the actual condition.

  3. Query the iSCSI IQN.

    iscsi-iname

    Information similar to the following is displayed:
    iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5

  4. Create a target using the queried IQN.

    targetcli /iscsi create Queried IQN

    Information similar to the following is displayed:

    server:~ # targetcli /iscsi create iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5
    Created target iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5.
    Selected TPG Tag 1.
    Created TPG 1.

  5. Run the following command to create a LUN:

    targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1/luns create /backstores/iblock/stonith_bd

    Information similar to the following is displayed:
    server:~ # targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1/luns create /backstores/fileio/stonith_bd
    Selected LUN 0.
    Created LUN 0.
    NOTE:
    • iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5 is the ID of iqn, which can be queried by running the targetcli ls command.
    • /backstores/iblock/stonith_bd is the Iblock device created in Step 3.

  6. Run the following command to create a portal:

    targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1/portals create

    Information similar to the following is displayed:

    server:~ # targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1/portals create
    Using default IP port 3260
    Automatically selected IP address 192.168.124.10.
    Created network portal 192.168.124.10:3260.
    NOTE:

    /iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5 is the ID of iqn in Step 5.

  7. Create an ACL.

    1. Run the following command to view the initiatorname.iscsi file and obtain value of InitiatorName:

      cat /etc/iscsi/initiatorname.iscsi

      server:~ #cat /etc/iscsi/initiatorname.iscsi
      InitiatorName=iqn.1996-04.de.suse:01:f3cdb3b6ea6a
    2. Run the following command to create an ACL using the value of InitiatorName:

      targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1/acls create iqn.1996-04.de.suse:01:f3cdb3b6ea6a

  8. Run the following command to disable the authentication:

    targetcli /iscsi/iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5/tpg1 set attribute authentication=0

  9. Run the following command to save the configuration:

    targetcli saveconfig

    NOTE:

    If an error is reported, locate the error, delete .aslist (), and save the configuration.

  10. Log in to the other two ECSs of the server side one by one and repeat Step 2 to Step 10 to configure the server side.

Client side configuration

  1. Log in to an SAP HANA node (client side) and attach the iSCSI disk of a server side ECS to the SAP HANA node.

    iscsiadm -m discovery -t sendtargets -p 10.0.3.250:3260

    iscsiadm -m node -p 10.0.3.250:3260 --login

    NOTE:
    • 10.0.3.250 is the IP address of the server side ECS and 3260 is the default port number of iSCSI.
    • Attach three iSCSI disks of three server side ECSs to the SAP HANA node.
    • You can run the fdisk –l command to view the newly attached disks.

  1. Run the following command to attach iSCSI disks automatically once the SAP HANA node starts:

    iscsiadm -m node -T iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5 -p 10.0.3.250 --op update -n node.startup -v automatic

    NOTE:
    • iqn.2003-01.org.linux-iscsi.scsi-0003.x8664:sn.38370da481a5 is the ID of iqn in Step 5.
    • 10.0.3.250 is the IP address of a server side ECS.

  2. Log in to other SAP HANA nodes and repeat Step 1 to Step 2 to configure all SAP HANA nodes of the client side.