iSCSI Setup with FlashArray

Required package on RHEL for iSCSI
iscsi-initiator-utils

Multipathing package
device-mapper-multipath

High level process with iSCSI

Setup iSCSI at the initiator
Setup Host at the FlashArray level
Discover the iSCSI targets
Login to the iSCSI targets
Create volumes, attach to the hosts, scan them and create the filesystems

1. To set up iSCSI at the host level, install the package iscsi-initiator-utils and start the iscsi service. Make sure to include the multipathing package as well.

yum install iscsi-initiator-utils 
yum install device-mapper-multipath
systemctl start iscsid
 [root@oraprod ~]# systemctl enable iscsid Created symlink from /etc/systemd/system/multi-user.target.wants/iscsid.service to /usr/lib/systemd/system/iscsid.service.
[root@oraprod ~]# systemctl start iscsid
[root@oraprod ~]# systemctl status iscsid ● iscsid.service - Open-iSCSI
Loaded: loaded (/usr/lib/systemd/system/iscsid.service; enabled; vendor preset: disabled)
Active: active (running) since Fri 2018-04-20 15:46:27 PDT; 4s ago
Docs: man:iscsid(8)
man:iscsiadm(8)
Process: 3468 ExecStart=/usr/sbin/iscsid (code=exited, status=0/SUCCESS)
 Main PID: 3471 (iscsid)
CGroup: /system.slice/iscsid.service
├─3470 /usr/sbin/iscsid
└─3471 /usr/sbin/iscsid Apr 20 15:46:27 oraprod systemd[1]: Starting Open-iSCSI...
Apr 20 15:46:27 oraprod iscsid[3468]: iSCSI logger with pid=3470 started!
Apr 20 15:46:27 oraprod systemd[1]: Started Open-iSCSI.
Apr 20 15:46:28 oraprod iscsid[3470]: iSCSI daemon with pid=3471 started!

Implement all the Linux best practices for FlashArray that can be found here.
https://support.purestorage.com/Solutions/Linux/Reference/Linux_Recommended_Settings

2. Setup the host at the FlashArray level by first getting the initiator’s IQN which can be found at /etc/iscsi/initiatorname.iscsi

Example:
[root@oraprod ~]# cat /etc/iscsi/initiatorname.iscsi InitiatorName=iqn.1988-12.com.oracle:abd254f8bba0

Go the Pure FlashArray, click Storage on the left frame and select the Hosts tab. Click the + sign on the right side to create a new host. Provide the IQN name you got from the initiator.

Configure IQN for a host in FlashArray Hosts

3. On the host, discover the iSCSI targets

$ iscsiadm -m discovery -t st -p <target IP address>

Example:

[root@oraprod ~]# iscsiadm -m discovery -t st -p 192.168.228.24
192.168.228.24:3260,1 iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5
192.168.228.25:3260,1 iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5
192.168.228.26:3260,1 iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5
192.168.228.27:3260,1 iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5

Configure IQN for a host in FlashArray Network

4. Create a volume on Pure FlashArray and attach to the host. Without a volume/lun attached to the host, trying to login to the target will result in following errors.

iscsiadm -m node –targetname iqn.2010-06.com.purestorage:flasharray.7b87f11aad2d06c8 -p 192.168.154.254 -l

Logging in to [iface: default, target: iqn.2010-06.com.purestorage:flasharray.7b87f11aad2d06c8, portal: 192.168.154.254,3260] (multiple)
iscsiadm: Could not login to [iface: default, target:  iqn.2010-06.com.purestorage:flasharray.7b87f11aad2d06c8, portal: 192.168.154.254,3260].
iscsiadm: initiator reported error (24 - iSCSI login failed due to authorization failure) iscsiadm: Could not log into all portals

5. Using the IQN information of the target, login to iSCSI target using iscsiadm command.

iscsiadm -m node –targetname <target iqn> -p <target IP address> –login

Example:

[root@oraprod ~]# iscsiadm -m node --targetname iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5 -p 192.168.228.24 --login
Logging in to [iface: default, target: iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5, portal: 192.168.228.24,3260] (multiple)
Login to [iface: default, target: iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5, portal: 192.168.228.24,3260] successful.
[root@oraprod ~]#

Login on all the iSCSI ports on the target. As of now, we have connected only to the first iSCSI target IP and hence Purity GUI shows Uneven paths. Run the above login command across all available iscsi paths .

Blog - iSCSI Setup with FlashArray - Connection Map

To login automatically on the host startup, run the following command to update the config at the host level. Do it on all the available iSCSI target IP addresses.

iscsiadm -m node -T <target iqn> -p <target IP> –op update -n node.startup -v automatic

Example:

[root@oraprod ~]# iscsiadm -m node --targetname iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5 -p 192.168.228.27 --op update -n node.startup -v automatic
[root@oraprod ~]# iscsiadm -m node --targetname iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5 -p 192.168.228.26 --op update -n node.startup -v automatic
[root@oraprod ~]# iscsiadm -m node --targetname iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5 -p 192.168.228.25 --op update -n node.startup -v automatic
[root@oraprod ~]# iscsiadm -m node --targetname iqn.2010-06.com.purestorage:flasharray.6fb3576b8af88fd5 -p 192.168.228.24 --op update -n node.startup -v automatic

You can verify if the iSCSI setup is successful by checking at the FlashArray GUI. Click Health on the left frame and go to the Connections tab. Look for the Paths against the host you just added. If it shows “Unused Port” and if you don’t see any entries against the host initiator it means the host has not logged into the target.

Blog - iSCSI Setup with FlashArray - Connections

Clicking on the “Unused Port” shows the connection map of the host ports.

Blog - iSCSI Setup with FlashArray - Unused Posts

After discovering and logging into the target from all the initiators, we can see that the Paths shows Redundant across all of them.

Blog - iSCSI Setup with FlashArray - Redundant

5. Create the volumes on Pure Flasharray and attach to the host.

6. Update /etc/multipath.conf or udev rules based on your standard operating procedures to create a persistent name for the multipath device.

     multipath {
 wwid 3624a93706c1d7213605f4920000117ed
 alias fs_prod_data01
 }
    multipath {
 wwid 3624a93706c1d7213605f4920000117ee
 alias fs_prod_data02
 }
    multipath {
 wwid 3624a93706c1d7213605f4920000117ef
 alias fs_prod_fra
    }

7. Scan for the devices on the host using rescan-scsi-bus.sh (sg3_utils package).

8. The devices should be available for use now.

[root@oraprod ~]# ls -ltr /dev/mapper/fs*
lrwxrwxrwx. 1 root root 8 May 1 17:57 /dev/mapper/fs_prod_data02 -> ../dm-11
lrwxrwxrwx. 1 root root 8 May 1 17:57 /dev/mapper/fs_prod_fra -> ../dm-12
lrwxrwxrwx. 1 root root 8 May 1 17:57 /dev/mapper/fs_prod_data01 -> ../dm-13

9. Use parted or fdisk to create the partition on the devices.

[root@oraprod ~]# ls -ltr /dev/mapper/fs* lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_data01p1 -> ../dm-14 lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_data01 -> ../dm-13 lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_data02p1 -> ../dm-15 lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_data02 -> ../dm-11 lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_fra1 -> ../dm-16 lrwxrwxrwx. 1 root root 8 May 1 18:06 /dev/mapper/fs_prod_fra -> ../dm-12

10. Create the filesystem on top of the partitions.

[root@oraprod ~]# mkfs -t xfs /dev/mapper/fs_prod_data01p1
meta-data=/dev/mapper/fs_prod_data01p1 isize=256 agcount=4, agsize=67108352 blks
 =         sectsz=512   attr=2, projid32bit=1
 =         crc=0        finobt=0, sparse=0
data =         bsize=4096   blocks=268433408, imaxpct=25
 =         sunit=0      swidth=0 blks
naming =version 2 bsize=4096   ascii-ci=0 ftype=1
log =internal log bsize=4096   blocks=131071, version=2
 =         sectsz=512   sunit=0 blks, lazy-count=1
realtime =none extsz=4096   blocks=0, rtextents=0

11. Mount the filesystem using _netdev option to make sure to inform the kernel that these filesystems should be mounted after all network interfaces are brought up to avoid missing device issues if it comes up earlier.

/dev/mapper/fs_prod_data01p1 /u02 xfs _netdev,nobarrier,noatime,discard 1 2
/dev/mapper/fs_prod_data02p1 /u03 xfs _netdev,nobarrier,noatime,discard 1 2
/dev/mapper/fs_prod_fra1 /u04  xfs _netdev,nobarrier,noatime,discard 1 2

Conclusion

FlashArray simplifies and enhances the iSCSI storage configuration process for RHEL systems, providing high-performance, scalable, and reliable storage solutions. By combining iSCSI initiator utilities, multipathing, and FlashArray’s user-friendly interface, administrators can seamlessly integrate volumes and ensure persistent device naming through udev rules or multipath configurations.

With FlashArray, users benefit from efficient volume management, redundant paths, and optimized connectivity to iSCSI targets, all of which contribute to improved data access and storage performance. These features are especially valuable for mission-critical applications, offering robust support for dynamic workloads while minimizing downtime and complexity. By following Linux best practices and leveraging FlashArray’s advanced capabilities, organizations can achieve a highly available, streamlined, and scalable storage environment tailored to their needs.