Mac Pro RAID setup
I recently posted about choosing a new storage solution for my Mac Pro where I decided to invest in an SAS based RAID system from www.rentaraid.co.uk. Now that the kit has been installed I thought I’d post a quick update about the installation procedure, an issue I ran into and the results so far.
Firstly, here’s a rundown of the kit I ordered and how it’s all setup. The PCIe card is the Areca AC-1882x 8 port SAS/SATA Raid adapter. This card features two external SAS connectors, each capable of controlling up to four SATA hard drives, hence the (8 port) description. Fitting the card into the Mac Pro is a relatively simple process, at least it is if you’re used to fiddling around with PCI cards. If you’ve grown up on iMacs then you might find this a little daunting but as long as your careful then fitting PCI cards is fairly straightforward.
One thing to take into consideration is that the SAS card is capable of utilising a x8 PCI slot. The slots in a 2010 Mac Pro are preconfigured so that the bottom two are x16 and the top two are x4. With my Nvidia Quadro 4000 GPU using the bottom slot the obvious choice for the new card was the next slot up. The card would still work if connected to a x4 slot but performance would be effected to some degree.
With older Mac Pro’s like the 2008 Model you can actually configure the slots in various ways using a utility that pops up when the Mac detects a PCI configuration change. I’m not sure whay the newer models don’t have that feature but anyway, it makes things simpler.
As you can see in the images above the card is locked into place by the bolt on locking place as well as a sliding bar which on the 2010 Mac Pro is locked and unlocked by pressing a small button on the fan assembly and sliding the assembly backwards and forwards. Next job is connecting a pair of miniSAS cables to the back of the card. The cables and connectors are large and very solid, they slide into the cards and fasten with a press button release mechanism. I numbered my cables and the Mac so that if I have to remove the cables at any point I could make sure to return them to the same position.
Now on to the drive enclosure. I went for an Enhance-Tech E-800MS 8 bay desktop enclosure, the same product is marketed in the US as the Proavio Editbox 8. When I unpacked the enclosure I was surprised how small it was, probably due to the image at the top of this post. Mine came from Rentaraid pre-installed with eight Hitachi Deskstar 7K3000 3TB Drives. Wiring up was very simple, just plug in the two SAS connectors, attach a power lead, and it’s ready to go. The enclosure is just a dumb device that holds and connects up the drives really, there’s no configuration necessary for the enclosure itself. Once connected up I switched on the Enclosure followed by the Mac Pro.
Booting the Mac Pro results in two loud beeps from the Areca card, this is normal for a cold boot. The card has a speaker built on to it so that it can warn you about any problems that may crop up with the array.
I had decided to install Mountain Lion on my Mac Pro previous to ordering the RAID kit and so made sure that the appropriate drivers for the card were available. Areca had a press release on their website stating that drivers for their SAS cards were included with Mountain Lion so I shouldn’t need to install any drivers… fingers crossed! Interestingly the Mountain Lion drivers are not available on the included CD or on the Areca website at the time of writing this.
Once at the desktop I looked at the system profiler and the card was showing as an SAS device, so far so good! The next job was to set up a RAID set… that’s where things started to get a little more complicated.
With something like a Drobo or a Pegasus system there’s going to be a slick installer app that you can run and follow the on screen prompts and options until your unit is ready to roll, nothing like that here!. The first challenge is getting to the admin utility which runs as a web based system on the card itself, it’s really just a case of typing http://127.0.0.1:81 into safari which brings up the following page but even figuring that out means trawling through a very in depth manual.
From there you can navigate into many pages of setup and maintenance options (See the bottom of this post for examples). Neil gave me some settings to use with the ‘quick create’ option which I followed and my RAID set was soon being built. Without those instructions though I can see a lot of people being stumped, it’s not user friendly at all unless your a systems admin.
I want to mention that Neil from Rentaraid.co.uk actually offers to remote into his clients machines and set everything up for them. The day my unit was delivered Neil was overseas so I decided to tackle it unattended with some written instructions instead… no patience me!
It took 15 hours for the RAID 5 set to build. Once complete the common ‘This Disk needs to be initialised” appeared on my screen and then once set to ‘Mac OS Extended’ I had a shiny new drive icon ready to be used. The first thing I did was run some tests on the RAID set using AJA’s System Test utility and it became apparent that something wasn’t quite right with the read speeds.
As you can see the read speeds are very erratic resulting in the green block you can see and the overall read results being lower the the write speeds. Sorry about the low quality image, it was captured by Neil using screen sharing software.
The next day Neil was back in the country so he remoted in to the mac and we tried various configuration settings to no avail. Neil even sent me a replacement Areca card to try but the results were the same. I tried installing the setup on my older 2006 Mac Pro running Lion and again the results were the same.
Not wanting to use up more of my time troubleshooting Neil had the kit picked up and sent it to the manufacturer who experimented with it for a couple of days and then sent it back to me along with their custom settings. So here’s the result from the same test after they configured it as RAID 5.
(See the bottom of this post for the card settings provided by Areca)
As you can see the results are very different now, instead of the erratic wash of green read speeds there’s a much steadier green line above the write speeds and the average reads results are in line with the write results at around 850 MB/s. So lets put that into perspective.
I have 21TB available on an RAID 5 solution that is more than ten times faster than my Drobo S and more than twice as fast as a 12TB Pegasus R6 running on a Thunderbolt connection. Although the initial cost is higher than both the Drobo and Pegasus solutions, the cost per TB is lower.
For comparison purposes Chris Fenwick has recently posted some examples of drives speeds using the same AJA test app. Chris tested the Pegasus R6 using thunderbolt and achieved read and write speeds of around 350 MB/s using RAID 5.
And how about Black Magics Disk Speed Test? Full House!
The only down side to using the Areca SAS card is that it’s not quite as easy to set up as some other options. If your a little more technically minded though or buy from somewhere like Rentaraid.co.uk that are happy to help with setup then it’s not something you should have to mess with very often.
Thunderbolt is useful and easy to use on laptops and iMacs but the thing to remember is that it does not perform as well as a Mac Pro’s PCIe slots. Having Thunderbolt on a Mac Pro would still be useful for offloading footage etc, but in terms of RAID storage you’re much better off with PCIe slots and a Mac Pro.
Words of Advice
I want to finish with two bits of RAID advice. Firstly, the Areca card has 1GB of built in cache memory that temporarily stores data during read and write actions. If you happen to lose power during a write session there’s a good chance that data will be lost and the RAID set might be damaged. There’s two ways to stop this happening. Firstly you can install a battery module on the card that keeps that data safe for a few hours and then writes it to the drives once the system is restarted. The second solution, and the one I chose was to install a UPS (Uninterruptible Power Supply). I picked up a reconditioned APC 1500 SmartUPS on ebay for £140 that keeps my Mac Pro and the enclosure running for around 20 minutes, in the event of power loss, it then communicates with the Mac Pro via USB and makes it shut down gracefully. If you buy a UPS for a Mac it needs to have ‘pure sine wave’ power output, not a stepped sine wave.
The other thing that you must do is backup your data! A RAID is not a backup solution, it can survive a disk failure but it’s a very complex system that can still suffer from failures resulting in the loss of all the data it holds. The other danger with 21TB of data on one drive is a human one, if you accidentally delete something, it can be a big something!
Over the next week or so I’m going to post about my backup solution, you just need to have a plan to recover all of the data should you lose the RAID, or the entire location where it lives.
If you’re interested in the Areca 1882 settings that Enhance-Tech supplied then I’ve included screen grabs below. Please bare in mind that these are specific to the Hitachi 7K3000 drives installed and the Enhance-Tech / Proavio E-800MS enclosure. The same may not work for different configurations.