HP Linux storage drivers: cciss vs. hpsa

HP has been transitioning away from the cciss Linux kernel-driver for a while now, but there hasn't been much information about what it all means. Just on the name alone the module needed a rename (one possible acronym of cciss: Compaq Command Interface for SCSI-3 Support), and it is a driver that has been in the Linux ecosystem a really long time (at least in the 2.2 kernel era). A lot has changed in the kernel.

HP has finally released a PDF describing the whole cciss vs. hpsa thing.

Read it here: http://h20000.www2.hp.com/bc/docs/support/SupportManual/c02677069/c02677069.pdf

The key differences:
  • HPSA is a SCSI driver, not a block-driver like CCISS
  • This means that the devices are moving from /dev/cciss to /dev
  • Device mode numbers will change
  • New controllers will increment kernel names, so a second controller will be /dev/sda, not /dev/sdb, so use udev names (partition ID, disk-ID, that kind of thing) to avoid pain.
  • For newer kernels (2.6.36+) cciss and hpsa can load at the same time if the system contains hardware that needs those drivers.