Mac Pro (Mid 2012 and earlier): Frequently Asked Questions about the Mac Pro RAID Card and Xserve RAID Card

This document contains frequently asked questions (FAQ) regarding the Mac Pro RAID Card and the Xserve RAID Card, with answers to those questions.
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Questions answered in this document:

Question: What are the Mac Pro RAID Card and the Xserve RAID Card?

Answer: The Mac Pro RAID Card and the Xserve RAID Card are internal RAID solutions for Mac Pro and Xserve respectively. There are two versions of each card, one released in April 2009, and one released in late 2007. To identify which version of the card you are using, see Mac Pro RAID Card: Identification and compatibility or Xserve RAID Card: Identification and compatibility.

Question: Are the drives hot-swappable?

Answer: All hard drives in the Xserve product line are hot-swappable; all hard drives in the Mac Pro product line are not hot-swappable.

Question: Do I need special software to administer the Mac Pro RAID Card or the Xserve RAID Card?

Answer: Normal administration can be carried out using the RAID Utility (found in /Application/Utilities) or by using the raidutil command. For more information refer to the User’s Guide or man raidutil.

Question: How can I administer the RAID remotely?

Answer: You can manage the RAID card by using Apple Remote Desktop to access RAID Utility or with remote login command line interface (CLI) tools, such as ssh and raidutil.

Question: My Mac Pro RAID Card is configured with a four-drive RAID 5 set and the available disk space is less than I expect. Why?

Answer: This is normal and expected behavior. Due to the way data is placed on a four-drive RAID 5 set, the total effective capacity is reduced. See Mac Pro RAID Card: Capacity for four-drive RAID 5 configurations may be different than expected for more information.

Question: Why can't I see my hard drives when my system starts up?

Answer: It is important to use the software that came with your computer. Check to make sure the card is functioning by starting up from the Install Disc that shipped with the computer.

Question: How will I know when there is an issue with my RAID?

Answer: An alert dialog box appears on the main screen when a user is logged in. This dialog box provides a brief description of the issue and the option to open the RAID Utility.

Question: Which drives does Apple support for the Mac Pro RAID Card and the Xserve RAID Card?

Answer: Only Apple SATA drives and Promise 450GB SAS Drive modules sold through the Apple Store are supported for use with the Mac Pro RAID Card (Early 2009) and the Xserve RAID Card (Early 2009). Apple 300GB SAS Drive modules are supported with the Mac Pro RAID Card (Late 2007) and Xserve RAID Card (Early 2007).  Drives must be either all Serial ATA (SATA) or all Serial Attached SCSI (SAS) drives. SSD drive modules are not recommended for the Apple RAID Card because these drives use their own on-disk cache and cannot take advantage of the protection provided by the battery-backed cache on the RAID card.

Question: Why does RAID Utility show a yellow light and report the status "Write cache disabled"?

Answer: The write cache is disabled automatically so data cannot be written to RAID volumes when the battery charge is not sufficient to back up cached data for 72 hours. This message is normally encountered when a RAID Card is used for the first time, when the battery enters a conditioning cycle once every three months, or when a computer with a RAID Card installed is shut down for any length of time.

If your RAID card's firmware is M- or later, or E- or later, you can use RAID Utility to force-enable the write cache while the battery conditions itself. Warning: If you enable the write caches before the battery is fully charged, you might lose some data if the power to your computer is interrupted.

Question: How often does the battery condition itself?

Answer: During normal operation, the battery will condition itself approximately every 3 months. You can view the date of the last conditioning cycle in the "Hardware RAID" section of Apple System Profiler. During a conditioning cycle, the battery is discharged and fully recharged to maintain battery life. It is important to let your computer complete the conditioning cycle by not powering down or rebooting the computer.

Question: How many watts of power does the Mac Pro RAID Card draw from the PCI Express bus?

Answer: The Mac Pro RAID Card uses a maximum of 26 W.

Question: Why am I receiving a warning "The Apple RAID Card installed in your system requires your attention" after rebooting?

Answer: If you do not clear out all alerts and warnings in Raid Utility, when the Xserve or Mac Pro reboots there will be a dialog box asking you to clear the warning. When all of the events are cleared, you will no longer receive this dialog on startup.

Question: Why won't my computer go into sleep mode?

Answer: The original RAID Card does not support sleep mode. The RAID Card introduced in 2009 supports sleep mode under certain conditions, as described in RAID Card (Early 2009): Enabling system sleep.

Question: Why can't I install Boot Camp on my Mac Pro or Xserve that uses a RAID?

Answer: Boot Camp does not support the installation of Windows onto a Mac using hardware or software RAID (Redundant Array of Independent Drives). Boot Camp is not supported on the Xserve with or without the Xserve RAID Card installed.

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