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Mac mini Maxi By: aeberbach Feb 8 2005 The Mac mini Maxi - how I attached extra storage to make a mini server. This article involves doing things to your Mac mini which may well destroy it. You should not try this unless you are prepared to lose your entire Mac mini investment, and you should definitely not try it if you do not have an appreciation for the dangers of power tools, electricity and the jagged edges found inside PC cases! When I woke up in Australia the morning after the MWSF keynote speech had come and gone, the Apple store timed out for 30 minutes or so before I was able to get my order in. It was a long wait until the 28th when the mini finally shipped, then the 31st before it was delivered. I wasted no time in getting the cover off and upgrading the memory, and was immediately impressed by this little machine. However 2.5" notebook hard drives are a serious limitation. For one they are limited to 100GB - I have more than that just in FLAC-encoded CDs, and I have half that much just in RAW-format images. The mini would make a great little server - quiet, cheap to buy new, low power too - if only big drives could be attached. Knowing that the mini uses 2.5" IDE drives I decided it was just a matter of making the physical connector right, and started this project about a week before I actually got the mini, luckily I guessed right. The speed increase that comes with using 7200 rpm drives is not to be sneezed at either (the largest 2.5" 7200 rpm drive I know of is just 60GB). There have been more than enough photo essays about unpacking the mini and disassembling it in various levels of detail. I'm going to jump right in and show you the part that mattered to me, the daughter board that connects the optical and hard drives to the mainboard. You won't see this view of it unless you disconnect both drives.  On the top is the optical drive connector. This is a standard connector but it's surface mount and difficult to buy - not something you can easily solder up at home. Below that is a 2mm-pitch 44-way connector, mating with a standard 2.5" drive - aha! Since I had adapters that let me use these drives in a desktop PC, I figured the reverse would be possible. And also I guessed that the optical and hard drives are simply master and slave devices on the IDE bus. A simple adapter would let me connect two normal IDE drives, be they optical or whatever. But while the adapter to connect 2.5" drives to a desktop machine is easily available, an adapter to connect 3.5" drives to a machine expecting 2.5" drives is not. Obviously 3.5" drives won't physically fit in laptops and there are different power requirements too so I could believe that such a thing wasn't available. Taking the easily available adapter and just reversing the sexes of the connectors might seem like an easy way to do this but then the positions of the pins are swapped - pin 1 would become pin 2, etc. - a sure way to damage the machine or the drive or both. Each pin must be mapped correctly to the same-numbered pin on the other side of the adapter. Where to put this server? Clearly 3.5" drives weren't going to fit in the mini's case. I settled on the Aopen H420B micro ATX case. If you're a switcher then Aopen might be a familiar name in cases. This is a fairly typical example of a PC case - steel sides, plastic front, clunky, covered in styling details that don't really help its looks. However it is roomy, comes with a power supply and as PC cases go is fairly compact. Another view shows that it is ready to house two 5.25" devices and a maximum of four 3.5" devices, although if you ask me stacking drives together in such a confined space is asking for heat-related trouble.  That this case is not as stylish as the mini isn't a big deal - its intended use is as a server, and it will be out of sight. I intend using it to store MP3s, images and video, and will stream music to various places around the house. It will share drives and be a convenient first backup location for work going on in my main machine.  As mentioned this case comes with a PC power supply. The mini also comes with a supply, and it requires 18.5V @4.5A which the PC supply can't provide. I decided to keep it simple and use both, the PC supply for the new drives and the mini supply for the mini. Normally the ATX supply is controlled by the PC motherboard and requires a pull-down on the control line (called by the ATX specification PS_ON#) to turn it on - you can make a PC supply turn on full time by connecting this signal to ground. I used a paper clip and then insulated it well - when the mains cord is attached it is on, when not attached it is off.  The PC power supply is required because of the different power requirements of desktop drives. A 2.5" drive requires a 5V supply only and is engineered with low power as a primary aim. A 3.5" drive requires 12V for the motor and 5V for the electronics and power doesn't matter so much because they are usually connected to big bulky ATX supplies of 300W or more. It might be possible to add some electronics to derive 12V from the mini's 18.5V - or it might be possible to take 12V somewhere from the mini's motherboard. I chose not to because it was not designed to do that, the PC supply was included, and taking too many steps at once is a great way to fail. That's an improvement for the future if everything else proves OK. Next comes mounting the mini. This case really works well with the mini - the ATX baffle pops out and the resulting hole is a great size to allow access to the mini's rear panel. Mounting points intended to hold a PC motherboard are in almost the perfect position to hold the mini's base in place, and the big rubber foot helps with friction. I decided to use the mini in its white base for two reasons - first, the GPU uses the metal shield as a heatsink. Second, I didn't want to make any modifications that couldn't easily be undone. In the end I decided the mount points were secure enough, and I just tied the base down using a couple of cable ties running through the rectangular holes around the base of the mini.  It is important to tie all grounds together. I connected the mini to the chassis using a small cable I made. This cable attaches at the front right side of the mini, between the plastic drive mount and the circuit board where there is a ground point and runs to a nearby motherboard mount.  The mini's power supply is mounted in a similar way. The opening for the cable to enter was the biggest modification to the case that I had to make, and involved filing open one of the PCI mounting slot holes.  Under the power supply are two pieces of thin, sticky rubber. They help to keep the supply unscratched and stop it from sliding toward the case front when you insert the power cable.  The PCB connecting the normal IDE cable to the daughter board was the hardest part of this project. I looked around but found only adapters allowing the use of 2.5" drives in desktop systems - it makes sense really because you can't physically fit a 3.5" drive in a laptop. So I made my own. This attaches to the mini's daughterboard, looking like a 2.5" drive to the mini, and connects a standard IDE cable.  With everything in the case it was time to attach some drives. I chose Maxtor Maxline Plus II 250GB drives, as they are intended for 24/7 "near-line" use. Other drives might be faster but these have a great reputation for reliability. I mounted the drives in Zalman ZM-2HC2 heatpipe hard drive coolers. I like these not for their garish looks but because they aid in cooling the drive - allowing heat to build up is the best way to cause drive failure - and because they allow mounting the drive in a 5.25" bay, again to help with cooling and it's a more convenient place for this project. As a side benefit the rubber mounts reduce transmitted noise - note the green wire at bottom left connecting the drive chassis to the case to keep everything grounded.  Finally came the big test - with everything attached I hit the switch. BONG...it's alive!  You can see in the top drive slot a Pioneer DVR-A05 optical drive, loading Mac OS X 10.3.7 (as supplied with the mini) from disc. Under that is the hard drive. Here's where my lack of Mac experience hurt - on entering the installer I didn't see the drive and I started to worry, checking jumpers several times. Finally I worked out that you have to enter Disk Utility to initialize a new drive before it shows up as available in the OS installer and all was well. This test over I attached a second 250GB drive, configured them as mirror (RAID 1) and reinstalled the OS from the disc. Server complete!  The final step was to add some more cooling. Hard drives like to be cool - it will not make them last longer than they otherwise would but allowing them to get hot will certainly shorten their lives. I had a nice filtered air intake lying around and found that a 120mm fan was just right in all dimensions to fit inside the plastic bezel. A little dremel work and that's it, the mini server is ready to have data transferred and be stowed away in the cupboard next to the UPS and switch. It isn't very loud (although certainly louder than a standard mini) but machines like this are great run headless and accessed through VNC software - there's just no need for a KVM when this isn't a machine you work on all the time.   Click here for a labeled version of the above image Future... 1. The ATX power supply is jumpered to be on all the time. I'm not so concerned about this since the server will be on all the time. What would work is to take a relay or some logic (74LS04) and use the 5V supply on the mini's drive connector (this is available on the adapter PCB) to control the PS_ON# line. Then the PC supply would turn off when the mini powered down the drives and turn on when the mini wanted the drives to be on. 2. As you can see from the rear picture the server requires two power cables. I needed to modify the case to allow access to the socket on the mini power supply. If I had opened up the PC power supply and connected the mini power cable to the back of the IEC socket (i.e. cutting off the plug, and soldering the wires) I would only have required a single cable - but that's a lot of work to eliminate a small inconvenience.  3. Work out a way to power the extra drives directly from the mini's supply, or find the requisite 12V ~2A supply (for two drives) on the mini's motherboard - this would make enhancements 1 & 2 unnecessary, but I don't think it is likely to be possible. 4. Make a desktop mini using large desktop drives - find a more elegant case, perhaps use a single (larger capacity) external supply to power both mini and drives. Such a machine will still make more noise than a mini but the G4's lower power requirements and fanless video will make it far quieter than most desktop machines. 5. Make a nice home theatre component using a rack-width case, perhaps 1U, adding firewire or USB accessories for video I/O. There has been a lot of talk about using minis for HTPC machines but with just one firewire port having to connect extra drives and I/O I think it might be difficult. Connecting big drives on the IDE bus makes it far more possible. The 3.5" to 2.5" drive adapter I'm calling it a success. I made it with two 40-way connectors for extra versatility. The lower one is for a male header and connects to an IDE cable. The upper one is for a female header and attaches the adapter directly to a 3.5" drive, in case your application involves a 44-way cable instead of the more usual 40-way. Some of these adapters are for sale and are available from me, both assembled and as bare PCBs. If you've ever had PCBs made you know that there's a standard charge for a standard-sized panel, and you may as well fit as many copies of your artwork on that panel as you can, so I have some spare. If you'd like to buy one please email me at hotmail.com - aeberbach is the username - and put IDE ADAPTER in the subject line, which will help me sort out your email from the huge volume of spam. Final thought Throughout the article I kept typing "Mini" but Apple don't use upper case, it's "mini". Could it be because of conflict with BMW group over their Mini trademark? To comment on this article please go to the forums here. |