iSCSI basics
In the world of iSCSI the following terms apply:
- the iSCSI server is called 'iSCSI target'
- the iSCSI client is called 'iSCSI initiator'.
To keep this wiki compatible to other guides the terms 'target' and 'initiator' are used as described above.
Warning:
Kernels before the version 3.2.0-38 include a bug with respect to iSCSI: As long as other technologies (e.g. LVM, multipath) still access iSCSI devices, every trial to log out of an iSCSI device leads to a non-recoverable kernel trace error. Only a restart of the host can recover from this error.
Even a restart or an update of the software package 'open-iscsi' can initiate such a log-out and thus lead to a kernel trace error. Data loss can be the result.
As a conclusion iSCSI must not be used on productive KVM hosts using a kernel version prior to version 3.2.0-38. All current Linux distributions meanwhile use more recent kernel versions.
The running kernel version can be found e.g. with uname:
root@kvm55:~# uname -r 3.2.0-43-generic