System volume is a small partition used for storing configuration of most services. If it is corrupted due to hardware problem you will not be able to access the data, even if it is on completely different device.
Each volume group has its own system volume, so in case one is corrupted you can switch to the other one (if you dont have backup of configuration just create new share/iscsi target with exiting volume to access the data).
What you should do now is to reinstall the os to make sure boot medium is ok, or boot it from flash drive and switch default volume group to other one to use other system volume.
If you need more help open a support ticket so support guys can help you.