Oracle Linux iSCSI Installation and Configuration

We are going to configure Oracle Linux for NetApp iSCSI storage use.

Software

Software used in this article:

  1. Oracle Linux 6.6
  2. device-mapper-multipath 0.4.9
  3. iscsi-initiator-utils 6.2

Note that NetApp configuration is not covered in this article.

Installation

Install device mapper multipath and iSCSI utils:

# yum install device-mapper-multipath iscsi-initiator-utils

Optionally, install lsscsi:

# yum install lsscsi

Configuration

Check for any SCSI devices:

# lsscsi
[0:0:0:0]  disk    HP   LOGICAL VOLUME  2.14  /dev/sda
[0:3:0:0]  storage HP   P244br          2.14  -

No SCSI devices found just yet, this is expected.

Configure Device Mapper Multipath

Open /etc/multipath.confand configure multipath. You most likely want to blacklist all local devices.

# grep -ve "^#" -ve "^$" /etc/multipath.conf
blacklist {
        devnode "sda"
        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
        devnode "^hd[a-z]"
        devnode "^cciss!c[0-9]d[0-9].*"
}
defaults {
        user_friendly_names yes
}
devices {
        device {
                vendor               "Netapp"
                product              "NewFiler"
                path_grouping_policy multibus
                path_selector        "round-robin 0"
                failback             immediate
        }
}

Start multipathd:

# service multipathd start

Configure multipathd to start at boot:

# chkconfig multipathd on

Configure iSCSI NICs

Our iSCSI NIC on /etc/sysconfig/network-scripts/ifcfg-eth4 is configured as follows:

# iSCSI1
DEVICE="eth4"
BOOTPROTO="static"
NM_CONTROLLED="yes"
ONBOOT=yes
DEFROUTE=no
PEERDNS=no
PEERROUTES=no
TYPE="Ethernet"
IPADDR=10.20.0.10
NETMASK=255.255.255.0

Our iSCSI NIC on /etc/sysconfig/network-scripts/ifcfg-eth5 is configured as follows:

# iSCSI2
DEVICE="eth5"
BOOTPROTO="static"
NM_CONTROLLED="yes"
ONBOOT=yes
DEFROUTE=no
PEERDNS=no
PEERROUTES=no
TYPE="Ethernet"
IPADDR=10.21.0.10
NETMASK=255.255.255.0

Configure iSCSI

Set up an iSCSI initiator’s name (IQN). The name must be unique to the iSCSI device we are connecting to.

Open /etc/iscsi/initiatorname.iscsi and modify the line similar to:

InitiatorName=iqn.1988-12.com.oracle:sql01.vb.local

The sql01.vb.local is a fully qualified domain name (FQDN) of our server.

There is no need to modify /etc/iscsi/iscsid.conf for login credentials as our NetApp is configured to allow access per VLAN basis.

Start iSCSI:

# service iscsi start

Configure iSCSI to start at boot:

# chkconfig iscsi on

Our NetApp IPs are as follows:

  1. 10.20.0.80
  2. 10.21.0.80

If your iSCSI NICs are configured properly, at this point you should be able to ping the NetApp IPs assuming no firewall is blocking ICMP traffic.

Discover the targets:

# iscsiadm -m discovery -t sendtargets -p 10.20.0.80:3260
# iscsiadm -m discovery -t sendtargets -p 10.21.0.80:3260

In case you get the following error:

iscsiadm: cannot make connection to 10.20.0.80: No route to host

Make sure you get your IPs on iSCSI eth4/eth5 NICs right. You may have mixed vlans and/or interfaces.

Set the logon as automatic:

# iscsiadm -m node -L automatic

When the LUN is ready, rescan iSCSI sessions to pic up the new LUN:

# iscsiadm -m session --rescan

Or restart iSCSI to pic up the new LUN:

# service iscsi restart

Check active iSCSI sessions:

# iscsiadm -m session
tcp: [1] 10.20.0.80:3260,2003 iqn.1992-08.com.netapp:sn.315:vf...
tcp: [2] 10.21.0.80:3260,2001 iqn.1992-08.com.netapp:sn.315:vf...

Chec the current multipath topology:

# multipath -ll
mpathb (4c355bafa5e8442dc5fb6e6577c6c92e) dm-4 NETAPP,LUN
size=250G features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=2 status=active
  |- 1:0:0:0 sdb 8:16 active ready running
  `- 2:0:0:0 sdc 8:32 active ready running

List iSCSI devices:

# lsscsi
[0:0:0:0]    disk    HP       LOGICAL VOLUME   2.14  /dev/sda
[0:3:0:0]    storage HP       P244br           2.14  -
[3:0:0:0]    disk    NETAPP   LUN              820a  /dev/sdb
[3:0:0:1]    disk    NETAPP   LUN              820a  /dev/sdd

We can now use /dev/mapper/mpathb for partitioning and then add to fstab (_netdev).

Example for how to create a logical 200GB ext4 formatted volume and mounted on /fra is below.

# pvresize /dev/mapper/mpathb
# vgcreate vg_fra-lun /dev/mapper/mpathb
# lvcreate --size 200G --name lv_fra vg_fra-lun
# mkfs.ext4 -m1 /dev/mapper/vg_fra--lun-lv_fra
# mkdir /fra
# mount -o defaults,_netdev /dev/mapper/vg_fra--lun-lv_fra /fra

Do not forget to add mounts to fstab /etc/fstab.

References

https://kb.wisc.edu/page.php?id=15607

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