03-08-2018 07:27 AM
is you question related to Brocade SAN Switches ?
if yes, please specified a bit more with Switch Type / model, FOS Version etc....
03-08-2018 10:59 PM
Antonio and Nate are right but given the fact I work for that company I'll touch on it lightly.
Host Mode setting is OS dependant so this selects basically the standard instruction set for a particular OS. If that is set incorrectly some SCSI commands may be interpreted differently whith unpredictable results.
HMO (Host Mode Options) are simply flags of which functions and features are enabled or disabled in the array for that specific host.
As an example VMware VAAI support can be enabled on all Host-groups but doesn't make sense if the host is AIX or Linux. That's why it is disabled by default.
The impact is impossible to predict if HM/HMO are set incorrectly. It can lead to data-loss, corruption, drive disconnect of simply commands being ignored.
Simply said, check twice before you do anything. This is not only related to Hitachi arrays but goes for all vendors.