SCSI Drivers Loading Order

• The mid-layer driver must be loaded before the others.
• When an HBA driver is loaded, it causes the mid-layer to perform a SCSI scan, in order to find any LUNs accessible to it, and attach upper-layer devices to them.
• This means that the order of HBA drivers loading is crucial to device naming: if we have HBA 1 that sees disk A, and HBA 2 that sees disk B, loading the the driver for HBA 1 first, will mean that disk A will be seen via /dev/sda, while disk B will be seen via /dev/sdb.
• In a SAN this is even more problematic - the order of discovery of different RAIDs will change the target ID (and device file attaching) for them. Anyone said "data corruption"?

Originally written by guy keren