ISCSI Initiator with Linux: Difference between revisions

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m (Text replacement - "</source" to "</syntaxhighlight")
Line 37: Line 37:
       search:
       search:
       - domain.de
       - domain.de
</source>
</syntaxhighlight>


=== Two dedicated 10GE interfaces with jumbo-frames for the backend ===  
=== Two dedicated 10GE interfaces with jumbo-frames for the backend ===  
Line 64: Line 64:
       match:
       match:
         macaddress: a0:36:9f:d4:cd:18
         macaddress: a0:36:9f:d4:cd:18
</source>
</syntaxhighlight>


=== Apply the parameters and check settings ===
=== Apply the parameters and check settings ===
Line 95: Line 95:
inet6 fe80::302d:f2ff:fed0:e23f/64 scope link
inet6 fe80::302d:f2ff:fed0:e23f/64 scope link
valid_lft forever preferred_lft forever
valid_lft forever preferred_lft forever
</source>
</syntaxhighlight>


=== Check if all components are configured right for jumbo-frames ===
=== Check if all components are configured right for jumbo-frames ===
Line 116: Line 116:
3 packets transmitted, 3 received, 0% packet loss, time 2055ms
3 packets transmitted, 3 received, 0% packet loss, time 2055ms
rtt min/avg/max/mdev = 0.191/0.196/0.202/0.004 ms
rtt min/avg/max/mdev = 0.191/0.196/0.202/0.004 ms
</source>   
</syntaxhighlight>   
If it does not has success, one of the switches on the way or the iSCSI-storage misses jumbo-frame settings.
If it does not has success, one of the switches on the way or the iSCSI-storage misses jumbo-frame settings.


Line 124: Line 124:
<source>
<source>
# /sbin/iscsi-iname
# /sbin/iscsi-iname
</source>
</syntaxhighlight>


The result is in /etc/iscsi/initiatorname.iscsi
The result is in /etc/iscsi/initiatorname.iscsi
Line 136: Line 136:
## for each iSCSI initiator.  Do NOT duplicate iSCSI InitiatorNames.
## for each iSCSI initiator.  Do NOT duplicate iSCSI InitiatorNames.
InitiatorName=iqn.1993-08.org.debian:01:4efdaa48c123
InitiatorName=iqn.1993-08.org.debian:01:4efdaa48c123
</source>
</syntaxhighlight>


=== Setup iSCSI-Interfaces ===
=== Setup iSCSI-Interfaces ===
Line 151: Line 151:
...
...
# END RECORD
# END RECORD
</source>
</syntaxhighlight>
<source lang=bash>
<source lang=bash>
# iscsiadm -m iface -I iscsi1 -o new
# iscsiadm -m iface -I iscsi1 -o new
Line 164: Line 164:
...
...
# END RECORD
# END RECORD
</source>
</syntaxhighlight>


=== Discover LUNs that are offered by the storage ===
=== Discover LUNs that are offered by the storage ===
Line 177: Line 177:
iscsiadm: connection login retries (reopen_max) 5 exceeded
iscsiadm: connection login retries (reopen_max) 5 exceeded
10.250.71.1:3260,1 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1
10.250.71.1:3260,1 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1
</source>
</syntaxhighlight>
<source lang=bash>
<source lang=bash>
# iscsiadm -m discovery -t st -p 10.251.71.1
# iscsiadm -m discovery -t st -p 10.251.71.1
Line 188: Line 188:
iscsiadm: connection login retries (reopen_max) 5 exceeded
iscsiadm: connection login retries (reopen_max) 5 exceeded
10.251.71.1:3260,2 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1
10.251.71.1:3260,2 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1
</source>
</syntaxhighlight>




Line 200: Line 200:
Logging in to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] (multiple)
Logging in to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] (multiple)
Login to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] successful.
Login to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] successful.
</source>
</syntaxhighlight>


=== Take a look at the running session ===
=== Take a look at the running session ===
Line 237: Line 237:
                 iSCSI Session State: LOGGED_IN
                 iSCSI Session State: LOGGED_IN
                 Internal iscsid Session State: NO CHANGE
                 Internal iscsid Session State: NO CHANGE
</source>
</syntaxhighlight>




Line 250: Line 250:
tcp: [2] 10.250.71.1:3260,1 iqn.2006-
tcp: [2] 10.250.71.1:3260,1 iqn.2006-
08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 (non-flash)
08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 (non-flash)
</source>
</syntaxhighlight>


=== Enable automatic startup of connection ===
=== Enable automatic startup of connection ===
Line 256: Line 256:
# iscsiadm -m node --op=update -n node.conn[0].startup -v automatic
# iscsiadm -m node --op=update -n node.conn[0].startup -v automatic
# iscsiadm -m node --op=update -n node.startup -v automatic
# iscsiadm -m node --op=update -n node.startup -v automatic
</source>
</syntaxhighlight>
=== Check timeout parameter ===
=== Check timeout parameter ===
<source lang=bash>
<source lang=bash>
Line 264: Line 264:
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 |  grep node.session.timeo.replacement_timeout
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 |  grep node.session.timeo.replacement_timeout
node.session.timeo.replacement_timeout = 120
node.session.timeo.replacement_timeout = 120
</source>
</syntaxhighlight>
=== Adjust timeout values to your needs ===
=== Adjust timeout values to your needs ===
<source lang=bash>
<source lang=bash>
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1  -o update -n  node.session.timeo.replacement_timeout -v 10
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1  -o update -n  node.session.timeo.replacement_timeout -v 10
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1  -o update -n  node.session.timeo.replacement_timeout -v 10
# iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1  -o update -n  node.session.timeo.replacement_timeout -v 10
</source>
</syntaxhighlight>


== Configure multipathing ==
== Configure multipathing ==
Line 279: Line 279:
[12:0:0:1]  disk    HUAWEI  XSG1            4305  /dev/sdb  <--- this is our iSCSI-storage
[12:0:0:1]  disk    HUAWEI  XSG1            4305  /dev/sdb  <--- this is our iSCSI-storage
[13:0:0:1]  disk    HUAWEI  XSG1            4305  /dev/sdc  <--- this is our iSCSI-storage
[13:0:0:1]  disk    HUAWEI  XSG1            4305  /dev/sdc  <--- this is our iSCSI-storage
</source>
</syntaxhighlight>


=== Get wwids for devices ===
=== Get wwids for devices ===
Line 289: Line 289:
# /lib/udev/scsi_id --whitelisted --device=/dev/sdc
# /lib/udev/scsi_id --whitelisted --device=/dev/sdc
3628dee5100f846b5243be07d00000004
3628dee5100f846b5243be07d00000004
</source>
</syntaxhighlight>


=== Setup multipathing configuration ===
=== Setup multipathing configuration ===
Line 323: Line 323:
   }
   }
}
}
</source>
</syntaxhighlight>


=== Startup multipathing ===
=== Startup multipathing ===
Line 336: Line 336:
<source lang=bash>
<source lang=bash>
# multipath -r
# multipath -r
</source>
</syntaxhighlight>
<source lang=bash>
<source lang=bash>
# multipath -ll
# multipath -ll
Line 344: Line 344:
   |- 12:0:0:1 sdb 8:16 active ready running
   |- 12:0:0:1 sdb 8:16 active ready running
   `- 13:0:0:1 sdc 8:32 active ready running
   `- 13:0:0:1 sdc 8:32 active ready running
</source>
</syntaxhighlight>


<source lang=bash>
<source lang=bash>
# ls -al /dev/mapper/data
# ls -al /dev/mapper/data
lrwxrwxrwx 1 root root 7 Okt 18 14:46 /dev/mapper/data -> ../dm-0
lrwxrwxrwx 1 root root 7 Okt 18 14:46 /dev/mapper/data -> ../dm-0
</source>
</syntaxhighlight>


=== Create a systemd unit to mount it at the right time during boot ===
=== Create a systemd unit to mount it at the right time during boot ===
<source lang=bash>
<source lang=bash>
# systemctl edit --force --full data.mount
# systemctl edit --force --full data.mount
</source>
</syntaxhighlight>


==== /etc/systemd/system/data.mount ====
==== /etc/systemd/system/data.mount ====
Line 369: Line 369:
Type=xfs
Type=xfs
Options=defaults
Options=defaults
</source>
</syntaxhighlight>


=== Enable your unit on next reboot and start it for now ===
=== Enable your unit on next reboot and start it for now ===
Line 375: Line 375:
# systemctl enable data.mount
# systemctl enable data.mount
# systemctl start  data.mount
# systemctl start  data.mount
</source>
</syntaxhighlight>
=== Check for success ===
=== Check for success ===
<source lang=bash>
<source lang=bash>
Line 381: Line 381:
Filesystem      Size Used Avail Use% Mounted on
Filesystem      Size Used Avail Use% Mounted on
/dev/mapper/data  10T  72G  10T  1% /data
/dev/mapper/data  10T  72G  10T  1% /data
</source>
</syntaxhighlight>


== Further reading ==
== Further reading ==

Revision as of 16:27, 25 November 2021


iSCSI with jumbo-frames and multipathing

Configure networking

LACP-bonding for the frontend

/etc/netplan/bond0.yaml

<source lang=yaml> network: 

 version: 2
 renderer: networkd
 ethernets:
   eno1:
     dhcp4: false
     dhcp6: false
     optional: true
   eno2:
     dhcp4: false
     dhcp6: false
     optional: true
 bonds:
   bond0:
    interfaces:
    - eno1
    - eno2
    parameters:
      lacp-rate: slow
      mode: 802.3ad
      transmit-hash-policy: layer2
    addresses:
    - 10.71.112.135/16
    gateway4: 10.71.101.1 
    nameservers:
      addresses:
      - 10.71.111.11
      - 10.71.111.12
      search:
      - domain.de

</syntaxhighlight>

Two dedicated 10GE interfaces with jumbo-frames for the backend

/etc/netplan/iscsi.yaml

<source lang=yaml> network: 

 version: 2
 renderer: networkd
 ethernets:
   enp132s0f0:
     dhcp4: false
     dhcp6: false
     mtu: 9000
     addresses:
       - 10.250.71.32/24
     set-name: iscsi0
     match:
       macaddress: a0:36:9f:d4:cd:1a
   enp132s0f1:
     dhcp4: false
     dhcp6: false
     mtu: 9000
     addresses:
       - 10.251.71.32/24
     set-name: iscsi1
     match:
       macaddress: a0:36:9f:d4:cd:18

</syntaxhighlight>

Apply the parameters and check settings

<source lang=bash>

  1. netplan apply
  2. ip a sh iscsi0

7: iscsi0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP group default qlen 1000 link/ether a0:36:9f:d4:cd:1a brd ff:ff:ff:ff:ff:ff inet 10.250.71.32/24 brd 10.250.71.255 scope global iscsi0 valid_lft forever preferred_lft forever inet6 fe80::a236:9fff:fed4:cd1a/64 scope link valid_lft forever preferred_lft forever

  1. ip a sh iscsi1

5: iscsi1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP group default qlen 1000 link/ether a0:36:9f:d4:cd:18 brd ff:ff:ff:ff:ff:ff inet 10.251.71.32/24 brd 10.251.71.255 scope global iscsi1 valid_lft forever preferred_lft forever inet6 fe80::a236:9fff:fed4:cd18/64 scope link valid_lft forever preferred_lft forever

  1. ip a sh bond0

12: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 32:2d:f2:c0:e2:3f brd ff:ff:ff:ff:ff:ff inet 10.71.112.135/16 brd 10.71.255.255 scope global bond0 valid_lft forever preferred_lft forever inet6 fe80::302d:f2ff:fed0:e23f/64 scope link valid_lft forever preferred_lft forever </syntaxhighlight>

Check if all components are configured right for jumbo-frames

<source lang=bash>

  1. ping -c 3 -M do -s 8972 -I iscsi0 10.250.71.1

PING 10.250.71.1 (10.250.71.1) from 10.250.71.32 iscsi0: 8972(9000) bytes of data. 8980 bytes from 10.250.71.1: icmp_seq=1 ttl=64 time=0.227 ms 8980 bytes from 10.250.71.1: icmp_seq=2 ttl=64 time=0.187 ms 8980 bytes from 10.250.71.1: icmp_seq=3 ttl=64 time=0.198 ms --- 10.250.71.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2045ms rtt min/avg/max/mdev = 0.187/0.204/0.227/0.016 ms

  1. ping -c 3 -M do -s 8972 -I iscsi1 10.251.71.1

PING 10.251.71.1 (10.251.71.1) from 10.251.71.32 iscsi1: 8972(9000) bytes of data. 8980 bytes from 10.251.71.1: icmp_seq=1 ttl=64 time=0.202 ms 8980 bytes from 10.251.71.1: icmp_seq=2 ttl=64 time=0.195 ms 8980 bytes from 10.251.71.1: icmp_seq=3 ttl=64 time=0.191 ms --- 10.251.71.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2055ms rtt min/avg/max/mdev = 0.191/0.196/0.202/0.004 ms </syntaxhighlight> If it does not has success, one of the switches on the way or the iSCSI-storage misses jumbo-frame settings.

Configure iSCSI

Setup initiator iqn

Setup a new iqn: <source>

  1. /sbin/iscsi-iname

</syntaxhighlight>

The result is in /etc/iscsi/initiatorname.iscsi

/etc/iscsi/initiatorname.iscsi

<source>

    1. DO NOT EDIT OR REMOVE THIS FILE!
    2. If you remove this file, the iSCSI daemon will not start.
    3. If you change the InitiatorName, existing access control lists
    4. may reject this initiator. The InitiatorName must be unique
    5. for each iSCSI initiator. Do NOT duplicate iSCSI InitiatorNames.

InitiatorName=iqn.1993-08.org.debian:01:4efdaa48c123 </syntaxhighlight>

Setup iSCSI-Interfaces

<source lang=bash>

  1. iscsiadm -m iface -I iscsi0 -o new
  2. iscsiadm -m iface -I iscsi0 --op=update -n iface.net_ifacename -v iscsi0
  3. iscsiadm -m iface -I iscsi0
  4. BEGIN RECORD 2.0-874

iface.iscsi_ifacename = iscsi0 iface.net_ifacename = iscsi0 iface.ipaddress = <empty> iface.hwaddress = <empty> iface.transport_name = tcp ...

  1. END RECORD

</syntaxhighlight> <source lang=bash>

  1. iscsiadm -m iface -I iscsi1 -o new
  2. iscsiadm -m iface -I iscsi1 --op=update -n iface.net_ifacename -v iscsi1
  3. iscsiadm -m iface -I iscsi1
  4. BEGIN RECORD 2.0-874

iface.iscsi_ifacename = iscsi1 iface.net_ifacename = iscsi1 iface.ipaddress = <empty> iface.hwaddress = <empty> iface.transport_name = tcp ...

  1. END RECORD

</syntaxhighlight>

Discover LUNs that are offered by the storage

<source lang=bash>

  1. iscsiadm -m discovery -t st -p 10.250.71.1

iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: cannot make connection to 10.250.71.1: No route to host iscsiadm: connection login retries (reopen_max) 5 exceeded 10.250.71.1:3260,1 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 </syntaxhighlight> <source lang=bash>

  1. iscsiadm -m discovery -t st -p 10.251.71.1

iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: cannot make connection to 10.251.71.1: No route to host iscsiadm: connection login retries (reopen_max) 5 exceeded 10.251.71.1:3260,2 iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 </syntaxhighlight>


Login to discovered LUNs

<source lang=bash>

  1. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 --login

Logging in to [iface: iscsi0, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1, portal: 10.250.71.1,3260] (multiple) Login to [iface: iscsi0, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1, portal: 10.250.71.1,3260] successful.

  1. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 --login

Logging in to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] (multiple) Login to [iface: iscsi1, target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1, portal: 10.251.71.1,3260] successful. </syntaxhighlight>

Take a look at the running session

<source lang=bash>

  1. iscsiadm -m session -P 1

Target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 (non-flash) 

       Current Portal: 10.250.71.1:3260,1
       Persistent Portal: 10.250.71.1:3260,1
               **********
               Interface:
               **********
               Iface Name: iscsi0
               Iface Transport: tcp
               Iface Initiatorname: iqn.1993-08.org.debian:01:4efdaa48c123
               Iface IPaddress: 10.250.71.32
               Iface HWaddress: <empty>
               Iface Netdev: iscsi0
               SID: 1
               iSCSI Connection State: LOGGED IN
               iSCSI Session State: LOGGED_IN
               Internal iscsid Session State: NO CHANGE

Target: iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 (non-flash) 

       Current Portal: 10.251.71.1:3260,2
       Persistent Portal: 10.251.71.1:3260,2
               **********
               Interface:
               **********
               Iface Name: iscsi1
               Iface Transport: tcp
               Iface Initiatorname: iqn.1993-08.org.debian:01:4efdaa48c123
               Iface IPaddress: 10.251.71.32
               Iface HWaddress: <empty>
               Iface Netdev: iscsi1
               SID: 2
               iSCSI Connection State: LOGGED IN
               iSCSI Session State: LOGGED_IN
               Internal iscsid Session State: NO CHANGE

</syntaxhighlight>


Check the session is still ok after a restart of iscsid.service

<source lang=bash>

  1. systemctl status iscsid.service
  2. systemctl restart iscsid.service
  3. systemctl status iscsid.service
  4. iscsiadm -m session -o show

tcp: [1] 10.251.71.1:3260,2 iqn.2006- 08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 (non-flash) tcp: [2] 10.250.71.1:3260,1 iqn.2006- 08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 (non-flash) </syntaxhighlight>

Enable automatic startup of connection

<source lang=bash>

  1. iscsiadm -m node --op=update -n node.conn[0].startup -v automatic
  2. iscsiadm -m node --op=update -n node.startup -v automatic

</syntaxhighlight>

Check timeout parameter

<source lang=bash>

  1. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 | grep node.session.timeo.replacement_timeout

node.session.timeo.replacement_timeout = 120

  1. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 | grep node.session.timeo.replacement_timeout

node.session.timeo.replacement_timeout = 120 </syntaxhighlight>

Adjust timeout values to your needs

<source lang=bash>

  1. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20000:10.250.71.1 -o update -n node.session.timeo.replacement_timeout -v 10
  2. iscsiadm -m node -T iqn.2006-08.com.huawei:oceanstor:210028def5f846b5::20001:10.251.71.1 -o update -n node.session.timeo.replacement_timeout -v 10

</syntaxhighlight>

Configure multipathing

List SCSI devices

<source lang=bash>

  1. lsscsi

[0:2:0:0] disk DELL PERC H730 Mini 4.30 /dev/sda <--- this is our internal disk / raid [11:0:0:0] cd/dvd HL-DT-ST DVD+-RW GTA0N A3C0 /dev/sr0 [12:0:0:1] disk HUAWEI XSG1 4305 /dev/sdb <--- this is our iSCSI-storage [13:0:0:1] disk HUAWEI XSG1 4305 /dev/sdc <--- this is our iSCSI-storage </syntaxhighlight>

Get wwids for devices

<source lang=bash>

  1. /lib/udev/scsi_id --whitelisted --device=/dev/sda

361866da075bdee001f9a2ede2705b9ba

  1. /lib/udev/scsi_id --whitelisted --device=/dev/sdb

3628dee5100f846b5243be07d00000004

  1. /lib/udev/scsi_id --whitelisted --device=/dev/sdc

3628dee5100f846b5243be07d00000004 </syntaxhighlight>

Setup multipathing configuration

/etc/multipath.conf

<source> defaults { 

   user_friendly_names yes

} devices { 

 device {
   vendor                  "HUAWEI"
   product                 "XSG1"
   path_grouping_policy    multibus
   path_checker            tur
   prio                    const
   path_selector           "round-robin 0"
   failback                immediate
   no_path_retry           15
 }

} blacklist { 

 # devnode "^sd[a]$"
 # I highly recommend you blacklist by wwid instead of device name
    
 # blacklist /dev/sda by wwid
 wwid 361866da075bdee001f9a2ede2705b9ba

} multipaths { 

 multipath {
   wwid 3628dee5100f846b5243be07d00000004
   # alias here can be anything descriptive for your LUN
   alias data
 }

} </syntaxhighlight>

Startup multipathing

From the multipath(1) man page: 

-r Force a reload of all existing multipath maps. This command is delegated to the
multipathd daemon if it's running. In this case, other command line switches of the multipath
command have no effect.
-ll Show ("list") the current multipath topology from all available information (sysfs, the
device mapper, path checkers ...).

<source lang=bash>

  1. multipath -r

</syntaxhighlight> <source lang=bash>

  1. multipath -ll

data (3628dee5100f846b5243be07d00000004) dm-0 HUAWEI,XSG1 size=10T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw `-+- policy='round-robin 0' prio=50 status=active 

 |- 12:0:0:1 sdb 8:16 active ready running
 `- 13:0:0:1 sdc 8:32 active ready running

</syntaxhighlight>

<source lang=bash>

  1. ls -al /dev/mapper/data

lrwxrwxrwx 1 root root 7 Okt 18 14:46 /dev/mapper/data -> ../dm-0 </syntaxhighlight>

Create a systemd unit to mount it at the right time during boot

<source lang=bash>

  1. systemctl edit --force --full data.mount

</syntaxhighlight>

/etc/systemd/system/data.mount

<source lang=inifile> [Unit] Before=remote-fs.target After=iscsi.service Requires=iscsi.service After=blockdev@dev-mapper-data.target

[Mount] Where=/data What=/dev/mapper/data Type=xfs Options=defaults </syntaxhighlight>

Enable your unit on next reboot and start it for now

<source lang=bash>

  1. systemctl enable data.mount
  2. systemctl start data.mount

</syntaxhighlight>

Check for success

<source lang=bash>

  1. df -h /dev/mapper/data

Filesystem Size Used Avail Use% Mounted on /dev/mapper/data 10T 72G 10T 1% /data </syntaxhighlight>

Further reading

External link collection: 

   • https://linux.dell.com/files/whitepapers/iSCSI_Multipathing_in_Ubuntu_Server.pdf
   • https://www.suse.com/support/kb/doc/?id=000019648
   • https://ubuntu.com/server/docs/service-iscsi
   •
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