Friday, June 25, 2010

Replacing or upgrading hard drives in an Apple Drive Module for a Mac server

Replacing the hard drive in an Apple Drive Module (ADM) is relatively simple, at least on an Xserve G5. I wanted to increase the server's storage capacity, so I picked up three Western Digital 1TB Caviar Blue (WD1EALS-00Z8A0) drives. I read a post that says the XServe G5 only supports up to 1TB drives. Otherwise I would've gone with some 2TB drives instead. The true ADMs only come in sizes up to 500GB for the G5 Xserve, and that's what I already have. The hard drives within the modules are Hitachi Deskstar 500GB SATA drives (HDS725050KLA360). I saw SATA and figured it must be pretty easy to swap them, and it turns out I was correct. However, there are some pros and cons of using stock, third-party hard drives in your Xserve G5. If you want to read the article I found, check it out here. Otherwise, here's the quick version

Pro - cheap, readily available

Cons - lack Apple-specific firmware, normally aren't server-grade drives, they haven't been tested by Apple, and the rubber washers on the ADMs are supposedly specific to certain drives for reducing vibration

Looking at that list I chose cheap. The only cons that would be a little concerning are that they're not server-grade drives, and they don't have the Apple firmware. However, the drives showed up in Server Monitor like normal so I don't know how much of an issue the generic firmware would cause. You could always test the drives yourself, and I don't think a different type of rubber washer is going to change the vibration in my drives enough to worry about it. It's up to you to gauge whether this is a good idea for your particular situation. For me it was fine so I proceeded with the swap. I have a Dual 2.3GHz G5 Xserve, which happens to use SATA drives. If yours is a different model you'll want to double-check what type of drives you need first. The ADM has a special connector on it for where it plugs in to the server., but it's just an additional interface and is not specific to the hard drive you buy. In my case the connector looked like this

Anyway, on to the hard drive swap. Here's how I did it:

1. Remove your ADMs from the server. Make sure to label the drives in them if they're in a RAID configuration so you can put them back in in the correct order if you need to. Putting them in in the wrong order will break your RAID. At this point you will have to
2. Once the drives have been labeled, take one and start removing the screws. There are four screws, two on each side. Remove them in whichever order you prefer. I removed one side first, then flipped it over and removed the other

3. Once the screws are removed you're going to have to remove the drive from the ADM. Set the drive flat on your work surface. Lift it up from the back of the drive, which is the side with the spring latch you used to remove it from the server. It should come out easily.

4. The SATA connectors will be on the front side of the ADM/drive, so flip the drive 180 degrees so it sits on its top. This will give you clear access to the SATA connectors. Unplug them

5. Now you have an empty ADM sled. Simply perform the steps in reverse. Plug in the connectors, flip the new drive into the sled, put the four screws back in and you're done.

This will leave you with an ADM with a new hard drive. Go ahead and repeat for any additional hard drives you're going to swap. Then put the ADMs back in your server and boot to the OS X Server install CD/DVD to get on with installing OS X Server. Don't worry if your server starts beeping at you after you've put in the new drives. That's the megaraid controller alarm letting you know that something is different than it expected with the drives. You can shut that off by going into Terminal after booting from the CD and using the command megaraid -alarm -silence. You'll have to use the megaraid program through the Terminal for configuring your new RAID array as well. For some examples of a configuration using the megaraid program, check out Otherwise you can enter megaraid in Terminal and see the few command line switches are enough to get you going. Good luck!


Anonymous said...

How did the new drives work for you? Issues? Thank you.

rslygh said...

I did have more issues with the server after a while, but never bothered trying to track it down and completely replaced it. I think the drives were fine because the issue was still the same, so I suspect it was the RAID controller.