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Fix iSCSI login errors

A few solutions for iSCSI log-in errors are known. They are described in the next sections.

Checking the iSCSI configuration

If the iSCSI login was possible before and the configuration was not changed manually, a misconfiguration will not be very likely - especially when the configuration is distributed by Puppet.
If Puppet is used and if in doubt, the configuration can be updated like so:

root@kvm55:~# puppet agent -t

If a backup of the host was created with the help of rsnapshot, the iSCSI configuration can be compared to older configurations in order to find possible configuration errors.

In such a situation a detection of the configuration with the help of the command

root@kvm55:~# iscsiadm –m discovery

has to be prevented, because the execution of the command will certainly overwrite the current configuration files thus possibly overwriting passwords stored in the configuration files ultimately.

If in doubt, compare the passwords contained in die iSCSI configuration with those (hopefully) stored in the password databse:

root@kvm55:~# find /etc/iscsi/ -name default -print | xargs egrep -h "auth.username|auth.password"
node.session.auth.username_in = hp3par30
node.session.auth.password_in = OngunajG8thi7i
node.session.auth.username = Company_kvm55
node.session.auth.password = aer2Do8faithiV
node.session.auth.username_in = hp3par30
node.session.auth.password_in = OngunajG8thi7i
node.session.auth.username = Company_kvm55
node.session.auth.password = aer2Do8faithiV

If the iSCSI configuration has to be adapted and Puppet is in use for the distribution of the configuration, the configuration must not be changed locally as puppet will overwrite it at next execution. In such a case change the configuration that is distributed by puppet.

Restart the iSCSI interfaces

A complete restart of all iSCSI connections is possible like so:

root@kvm55:~# /etc/init.d/open-iscsi stop
root@kvm55:~# /etc/init.d/iscsi-network-interface restart
root@kvm55:~# /etc/init.d/open-iscsi start

If the iSCSI sessions don't get connected by open-iscsi start, login to iSCSI manually.

Wait before another log-in trial

Sometimes it is helpful to wait for 10 to 15 minutes before the next log-in trial. In some cases log-in was possible again after some waiting time. The reason for the time-out is unknown - maybe switches discard the MAC addresses after some time or the account will be locked temporarily after failed login attemtps.

When all log-in trials fail

In such a case it should be checked whether the log-in ever succeeded before. If this is not the case then maybe a wrong username or a wrong password was transferred to the user. If all else fails, ask the administrator to reset the password on the iSCSI device. Do not forget to update the configuration and the password in the password database afterwards!

Assignment between iscsi LUNs and SCSI devices

For further debugging it might be helpful to know the assignment between iSCSI LUNs and physical disks. The assignment can be displayed with the command lsscsi. Maybe the software package of the same name has to be installed before use:

root@kvm55:~# apt-get install lsscsi

A display of the SCSI devices can look like so:

root@kvm55:~# lsscsi
[4:2:0:0]    disk    LSI      MR9240-4i        2.13  /dev/sda
[5:0:0:0]    disk    3PARdata VV               3112  /dev/sdc
[5:0:0:1]    disk    3PARdata VV               3112  /dev/sde
[5:0:0:254]  enclosu 3PARdata SES              3112  -       
[6:0:0:0]    disk    3PARdata VV               3112  /dev/sdb
[6:0:0:1]    disk    3PARdata VV               3112  /dev/sdd
[6:0:0:254]  enclosu 3PARdata SES              3112  -       

In the code above the device '/dev/sda' is a local disk while '/dev/sdb', '/dev/sdc', '/dev/sdd', and '/dev/sde' are iSCSI LUNs.

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public/iscsi/fixes.txt · Last modified: 2015/10/29 13:42 by T Kornack