Along with all the iApp/iMac announcements yesterday, Apple quietly released an internal hardware RAID card for the Intel Xserve as well as a PCI Express RAID card for the Mac Pro.
Read on for more details…
While essentially performing the same job, there are some subtle differences between the hardware make-up between the card available for the Xserve, and the one for the Mac Pro. The Xserve RAID card does not use up one of your PCI slots, but it does replace the built-in SATA/SAS drive controller. This means that with the RAID card installed you need to use either all SAS or all SATA drives in your Xserve drive bays. It supports RAID levels 0, 1, 5, and Enhanced JBOD and has 256MB of cache along with an integrated 72-hour battery backup for protecting the RAID cache.
The Mac Pro card also has the 256MB of cache and integrated 72-hour battery backup (which is noted as being supported on OS X only) and has the same RAID levels that the Xserve card has, but adds to that RAID 0+1. It also installs into your top PCI Express slot (slot 4) in your Mac Pro rather than replacing the existing drive controller. While the Xserve RAID card supports both SAS and SATA, the Mac Pro only supports SATA drives.
New software has been released for setting up your new RAID sets called RAID Utility, and will install into /Applications/Utilities for the GUI, is also available during the installation process, and has a command-line option called "raidutil". Full documentation is available for both the GUI and Command Line tools in this manual from Apple – http://images.apple.com/server/docs/RAID_Utility_User_Guide.pdf . Of special note here, the ability to take an existing enhanced JBOD disk and convert it into a RAID volume in what is being referred to as migrating your RAID set. Migrating only works on enhanced JBOD disks and machines with the RAID card will come with the boot drive set up that way. Only the data on the enhanced JBOD drive will remain in tact – data on the remaining drives to be added to the RAID set will be destroyed.
Now the catch – all this is only available on new custom orders – in other words, if you want to use hardware RAID in either your Xserve or your Mac Pro you must configure the machine with it when you buy it. The cards are not available for purchase from the Apple store as a stand-alone product.
by 
Does anyone know whether Target Disk Mode is supported when using the hardware RAID controller in the Intel Xserve? My guess is that it is not supported, but I’m hoping…
Its pretty stupid that these cards are not available as a separate product. I know for a fact that a lot of companies/users would love to have them. I hope for Apple’s sake that this decision is simply because of supply issues or perhaps they’re simply testing the waters with this new addition. In the meantime, RocketRaid cards provide the same products/performance.
or we can hope, hope, hope that ZFS is for real coming to OS X Server – i, for one, and never going to put critical data on any filesystem other than ZFS, unless something better comes along.
the hardware RAID option might be better performance than ZFS (which i’m using for all my storage needs under Solaris Nevada b65), but ZFS has several important advantages:
data integrity checks in real-time
endian agnosticism
hardware agnosticism (any zpool from any machine can be swapped to another ZFS-aware system)
instant data-recovery from parity (with useful log output!)
i imagine Apple is selling the RAID controller as BTO only because most of their customer are Govt/Edu orgs that have comfy, taxpayer-provided budgets with which to simply replace, rather than upgrade, hardware :^)
—
blake irvin (blake at clockworm . com)
systems engineer, tribune review publishing company