Poor Mans Raid Array
What self-respecting geek doesn’t get the warm fuzzies at the mere mention of the RAID. With the rising GB to Dollar ratio, we felt it was a good time to feature a project that takes Pure Geekieness(TM) and mixes in a good helping of do it your self. Where else are you going to store all those MP3s (legally obtained, of course)? On a single 200 GB Drive? Or a RAID 5 Array? Take you pick, I know where I will be storing mine.
RAID is defined as: “Redundant Array of Independent Disks”, but core geeks would probably prefer the definition to be more along the line of… “RAID Kicks Ass!” For about 250.00 we have made a true 0.5 terabyte RAID 5 array. What are the advantages of a RAID array? In short, data availability. Rather than having your (legally obtained) MP3 collection on a single drive, it redundantly spans multiple drives. in this implementation we will also be using a “hot ready” so that in the event that a drive did fail the RAID controller can shutdown the drive, and start rebuilding the array to the hot ready on the fly. We will also be covering a method that uses software RAID, and a USB based interface. Then you can paint it to look like a big iPod and make your friends all jealous.
In this build out there are really only a couple requirements for the case. It has to have the ability to house several (14) drives all at the same time, and must be able to power them as well. The drives we used are a little different than your home grown normal variety, they are taller than normal. So normal cases can’t fit them in the normal 1 inch tall bay. The solution is very easy with this case, with 2 support rails inside and the hole patterns on the rails for normal drive spacing, we will be suspending the drives inside the case so we can get the most amount of storage in the smallest amount of space. Also this is the first project we have done that takes advantage of the rackmount form factor. When it comes to lots of equipment in a small space this is the best way to go. Because Rackmount Kicks Ass!
So all geeking aside, for this project we choose the Seagate Barracuda SCA SCSI line of drives. There are several models you can choose from, the “ST118273LC” 18.6 GB drive is readily available on eBay for about $5.00 a drive, or the “ST150176LC” 50.1 GB at about $15.00 each. I was fortunate enough to get a “Bulk Lot” of the 50 GB model for about $70.00. These drives can run very hot, and do require alot of cooling, so we will be modifying the case to improve airflow and keep the drives cool.
SCA to 68 pin SCSI Adapters
This is a really simple but critical part of the whole processes of this build. The drives we got are SCSI, but with a unique plug on the drive. Most SCSI devices can be converted, or adapted to other types, I.E. SCSI I to SCSI II. For this project we will be using the SCSI II interface for our cabling, and adapters and raid controller. Additionally, most SCA drives (like the ones we are using) don’t allow you to set the ID on the drive itself. The adapter has a bunch of jumpers that allows you to assign the drive a unique ID number up to 16 ID’s total with this particular adapter. They are readily available on eBay or from other online SCSI equipment vendors. They can be found from $2.00 – $8.00 each. We got ours for $4.00 each.
The Fan Array:
Heat is always a concern with any computer equipment. But here there are a few special concerns. The drives are all 10K RPM. So they run hotter than usual drives. In fact when idle they produce about 20.85 BTUs. When active they average about 71.2 BTUs! Factor in the fact that RAID solutions are usually about 25% more intense on hard drives, and that we have 14 of these drives in a single case and you can see why we have a potential problem with heat. Up to 996.8 BTUs for the array total! Another concern is that as a drive heats up it can actually affect the drive enough that it doesn’t write data consistently as the platters heat up and change shape. Personally I really hate hot platters, like the ones at Chili’s… I always get burned. So to handle this issue, we have come up with a custom fan array to whisk the air and heat away from those ever so expensive drives.
SCSI Raid Controler ( IBM ):
I’m a big fan of using the older technologies in more modern uses. The problem is that many companies like IBM have a habit of killing support for drivers. This is where my love for Linux comes in. I have yet to find an older RAID controller that doesn’t have drivers for Linux. So naturally with this in mind I went shopping for some good RAID controllers. The one I found that really stood above the rest was the IBM Server Ultra II RAID Controller model “76H3587”. This unit has 3 separate SCSI channels on it, supporting 16 devices per channel. Linux is totally friendly with it, and they sell on eBay consistently for about 11.00. The raid features on this card are really nice, good interface and setup for your arrays. It allows for the hot spare we all love and want oh so badly… well maybe just me.
Now, where is my hammer.
The project really centers around the right case. The case we are using I get and use frequently at my place of employment. The vendor we use for these cases is a local group called EBC Computers. Who knows what EBC stands for, this is not a plug for them, it’s just the only vendor for this case I have found…. any who the part number is CA-TT-R19-B-320 with them. The box is labeled with the brand IPC, but I have yet to find a similar case with the rails like this case has.
So what makes this case so special? The structural rails running from left to right as you see here. The rails are designed with the option of handing drives, or cooling fans from them. No other case I have found has 2 rails in them. Many have one rail. The second here is a bit of a scarcity. So now all we need to do is get rid of all the crap we don’t need. Be sure to save the odd bits for future projects.
The case is as empty as a Comdex convention without the Microsoft booth’s go go girls… we really removed everything we could here. The front fan plates, and fan, the drives, drive housing, the floppy housing, the hard drive mounts, speakers, the rear panel, and the motherboard mounting plate. Everything we could. With the case stripped you can really see just how much room we really have to work with in this case. There is alot more room for alot more drives if you used regular form factor drives in this mod. But that’s not what was doing here now is it….
So here is the pile of future project scrounging and idea giving crap we tore out of this case. As you can see the carnage is actually quite extensive. The motherboard mounting panel is the more interesting tidbit in this tearout I suppose. As the drive caddie mounts directly to it you could make an open air system, or a submerged system really easily with some minor tweaking.
Our first major move, the power supply frankly just is too much in the way in the case. The power supply is mounted to the case with a plate it screws to, and that plate mounts to the case itself. After careful inspection we chose to bump out the power supply to make room for more drives in the case. It took some trial and error on the spacing as we didn’t take into account the SCA to SCSI adapter’s depth. So learn from my mistake, factor in all given information before you make that final cut. We did have to move the power supply out far enough that the fan was actually half inside and outside the case. We moved the sticker to cover half of the fan so we could take full advantage of the extra fans pulling air out of the case.
We finally chose some aluminum posts and screws we found at Lowe’s to kick the power supply out from the case, and hold it securely. We had to drill out the holes to 1/8 to accommodate the larger size of the posts. But after we secured them tightly, the power supply wasn’t going anywhere. We ended up stacking 3 of the posts per rail to give the needed depth; it turned out to be about 3 inches.
So now we needed to hot wire the power supply. As there is not a motherboard to plug into, or control the power supply we have to jump some wires in the ATX connector. I believe we jumped the green and black right next to it. Here I used a piece of wire to make sure it would work. Later I took the same power supply and spliced into it with a rocker switch I got at Radio Shack, so I could power it on and off from the front of the case. Just a special note. Be careful when dinking around with electricity. There are some “dummy loads” out there for ATX power supply testing that will work just the same and not directly endanger your life.
Drives, drives, drives. Here is a close up shot of the drives I used. They are the same width and height as a normal drive, their thickness, however, is something unusual. There are SCA drives out there that are the normal thickness, just be careful what you buy when it comes to SCA drives. I had a friend order his drives to build out a similar project like this and he ended up getting all 5″ behemoths instead! If you are armed with the model number you can check Google or the manufacturer’s site and get really detailed specs on dimensions, power consumption and BTU output to help you make the most educated decision you can. Or….. You can modify an old filing cabinet to hold 35 5″ 9 GB drives.
So now to start hanging the drives. The rail’s holes line up with the drives perfectly. Mount the drives with a 1/2″ gap between them. You should be able to get 7 across very comfortably. Mount them so the SCA plug is facing the front of the case for the front rail, and facing the rear of the case with the rear rail. Make sure to ground out the case, drives, and your self before getting too involved here as the older SCA hardware seems to be more static sensitive.
So here is the case with all the drives installed. Very cool looking isn’t it? So at this point you may have to move it… the case and drives together will weigh about 50 LBS or so. So be careful not to hurt yourself here. Once you have the drives all mounted double check that all the screws are nice and tight.
So here is the SCA drive adapter. It’s a simple little device. Just a SCA plug on one side, and the power, 68 Pin and some jumpers on the other. The jumpers are what you use to assign each drive an ID in the chain. Assign your adapters their ID’s before you install them in the drives as it can be really tricky to change the settings when they are installed in the case. These are really rugged pieces of hardware, the only item of concern I had with them is the fit of the plug to the SCA adapter is a bit loose. Just enough that the adapter can rock forward and give the drive a 12V kiss, thus killing the drive. So just watch the spacing between the drive and these adapters.
So here is the final shot with all the SCSI cabling done, the Power run, and the jumpers set. I did have to use about 6 Power “Y” cables to get enough leads from the power supply we used. Be sure to keep the cabling tight and clean on this final step. The cleaner and tighter the cabling is the better the airflow in the chassis will be. So now all we really need to do is work on some cooling solutions and fire this one up.
Cooling The Beast…
Heat in this build is the strongest foe. Fourninately we have a vorpal heat slaying dagger with a +9 agent’s heat. In this build we will be doing a fair amount of fabrication of cooling devices. We will be taking advantage of the case its self to minimize the amount of raw / difficult fab work. So to cool this project adequately we will be using good old fashioned air, like the stuff you breathe. We will start with the front panel. Simply remove the panel from the chassis. The panel is simply a metal frame with a piece of smoky plexi attached with double sided sticky tape. Simply use a screw driver to separate the two. Using a dremal tool, or an 80mm hole saw and a drill, cut a hole in the plexi for the fan, and some smaller ones for the screws for the fan. Assemble the panel with fan and grill like it was. Super glue can more than hold it together if your tape fails, or you get it covered with sprinkles from the donut you’re eating at the time….
Reattach the modified panel to the server and make sure the alignment still allows it to open and close like it did prior to you fiddling with it. I also took the air filter out of the case to help promote airflow in the front of the case. One final thought on this step make sure you have your fan blowing the right way. Or you will have problems getting the desired result. Although the alternative could be fun to watch as well.
With the front blower finished we will be moving on the main blower array in the case. This is what causes the case to have a negative pressure and draw in the cooler air to keep those drives from glowing. Using a piece of cardboard, make a template of the hole where the rear panel was once located in the back of the case. Space out 3 fans on the cardboard and trace them on to it with screw holes as well. Carefully cut it out and use it as template to construct the same out of plexi. Use a dremal tool or 80mm hole saw for the main cutting. One tip I learned here is run the hole saw in reverse and melt through it. Some times the teeth can bind and shatter the plexi.
Assemble the fan array with fans on the back and front of the array (total of 6) stacking the fans will help increase the “bite” they have in moving air. Next chain the power all together and use twist ties to attach the cables to the plexi (drill additional holes if needed) and give it the shake test to see if the cables can move and can come into contact with the fans. Grills are optional here but always look cool. I mean come on, chrome and cars and chrome and computers that’s the something…. right?
Take the newly constructed fan array and carefully mount it to the case. Take care when tightening the screws not to over tighten them as it will cause the plexi to crack or even shatter. Take the power leads to the unit and attach them to the power supply. Fire up the up the server preferable with out power to the drives to verify that you are getting the airflow you need. Some fans operate at 4000 rpm and some at 2000 rpm. This will directly affect the amount of air you can move through the case. If you have the slower fans you can get nicer ones really cheap
Now with the fans tested and the drives wired, and the SCSI cables installed we can move on to firing up this monster. Double check all your connections and fans to make sure no surprises are awaiting you down the road. I recommend getting a small home thermostat with the little outside sensor and running it in the case just so you know exactly how hot it gets inside. Some double sided sticky tape or superglue on the front of the case to hold it in place and you should be good to go. Seal the case up and screw the cover on to make sure you have optimum airflow and fire it up. Just a word of caution again on heat with this unit. If you get it too hot, and you shut down the unit, the drives will not have anything cooling them, but the drives will still be radiating heat. The hottest this will get is when you shut it down after you have been running it. So shut it down long before you “have to” shut it down… or…. run the hell out of it, and use the top of the case as a skillet and start your own dinner….
Final setup and configuration:
Take the raid controller you have and install it in your case. A note on this, the IBM card we had shown earlier is a great card, its only drawback being that it is a full length card. Extremely long that is. So not likely to be used in a normal case. we had another raid controller laying around to test the drives and make sure our SCSI chains were all working like we wanted. Most older RAID controllers are PCI only. But there are allot of very affordable PCI-X or PCI-E cards out there also. Its up to you on the system spec you dump this all into.
We chose another rackmount server case to build out the final server configuration we went with. This allowed us to just run the SCSI ribbons out the back of the cases to the server. Having a dedicated server is definitely the way to go if your not going to be moving this allover the place. Although in the alternative configuration we did chose to use the Adaptec SCSI2USB devices to make this process simpler. We have a little tweaking to do with the terminators using them, but if you want a really plug and play type setup and don’t mind the overhead of software raid they are definitely the way to go. But a dedicated server is really handy for mp3 servers, bittorrant servers, and other socially questionable services and servers.
The final step here is just working with the raid controllers setup. We chose in this build to use a hot ready drive so if one failed we can have automatic failover to the ready drive. In the end we built out 2 of these units and added a second RAID controller to the server. Not too bad, the ole cost to TB ratio I think…
This has been a real unique build for me. So it turns out that this is allot more practical that I realized when the thought started stirring in the old noggin. But its not without its problem areas. For instance the heat factor is still something to contend with. I have actually built out an additional fan array that fits real well in the gap between the rails. It dropped the temperature of the drives by an additional 10 degrees. The one problem I needed to address in this build was the need for a second fan in the front of the case on the filter side of the case. This would have required some serious metal work to pull off.
Another down side I did run into is the limitation of the SCSI 2 based drives. They top out at about 20 Mbs. but that usually isn’t an issue with raid and a good raid controller with some memory onboard. All in all I have to say this is allot cooler rig than I thought it would be at first. One thing I would love to have had the time to do is build out a custom LED array for the drive activity lights. Each drive has its own LED and a unique LED jumper on them. With 2 of these units running 28 drives that’s one hell of a light show. The drives really light up with the raid 5 on them when data access is occurring. Running all the leds to a separate panel that has just a ton of apparently random flashing LEDS would be very cool, and functional as well. It acts as a visual indicator, or conbon of the drives status. So there you have it. The poor mans raid array. For under the price of a comparably sized drive you can have the ultimate redundant array of them. And that’s got to amount to a geek level up right?
Hi guys, I thought this a good chance to jump in here and discuss this project as i wrote it. So here some quick Q&A for all those opinions i have seen floating around on the ole www.
Q. Was this already dugg and there for not cool?
A. Yes it was. But a lot of peeps don’t seem to dig in the depths of Digg to often, so its always refreshing to get more eyes on a project, selfish as it may sound.
Q. Was this cool once?
A. I think it still is if you need a redundant cheep storage solution. This doesn’t have a lot of use other than archiving. When this project was originally done it was at a point that 2 or 4 drives were reaching a similar combined size affordably.
Q. Does onboard Raid suck?
A. Not for home users. Unless your overclocking your more likely to loose items with moving parts before motherboards.
Q. What is the better raid?
A. That depends on the application.. Raid 1/0 is really great for anyone that wants higher bandwidth and some redundancy. For a home user that’s really the best all around solution. High end raid 5 or 6 solutions in SCSI or Sata are great for business solutions, and Sata raid 5 solutions are becoming more affordable and standard on some high end consumer grade motherboards.
Q. Is it faster than Sata?
A. well if the bandwidth is what’s being referenced here then in this instance, No. The drives that were used run at basically SCSI2 or some where about 20 meg per seconds.
Q. is raid 5 better than other raid types?
A. Yes and No. you see its all about application of raid. For instance raid 5 is a 90% read to 10% write type architecture. So if your reading a lot its less latent and much more redundant than other solutions. Also it gives you the ability of a hot spare so in the event that a drive fails then you can have the array rebuild on the fly. Also its dynamically scaleable, you would need a very expensive Sata raid controller to provide something comparable.
Q. Is it out of date?
A. For 99.9% of users.. Yes. But its still cool!
Q. Is it a power hog?
A. No more than a standard 450 watt computer. It uses the same power supply.