Netgear Switch GS748T GS724T Loud Fan Swap Modification
Introduction
The other day I picked up a Netgear GS748T 48-Port Gigabit Switch. Price-wise the switch was hard to beat considering the included feature set and density of ports all in one handsome package. The web interface is a bonus, but I will get to that later. I plugged in my switch and to my astonishment heard the full furry of 3 40mm internal fans raging at full strength. My first thought was a hopeful pause while I waited for the fans to throttle down after initial boot, but that never happened. Granted this switch was intended for the server room environment, and noise considerations are rarely a factor in a rack-dense world of competing spinners for loudest hum.
So I wasn’t going to let this loud switch put a damper on my excitement over a litany of other quality features. I ventured fourth and started pulling screws to see what I could do with this particular piece of hardware. The switch shell came apart quite easily (3 screws on each side and two on the bottom faceplate). I was joyed to find three industry standard fans (1x 40x40x20mm, 2x 40x40x10mm). After looking up the specs on the factory fans I saw that the 40×20 was moving 10 CFM @ 33 dBA while the 40×10 was moving 10 CFM @ 37 dBA. I knew I could do better than that with the great selection of fans on the market.
Gritty Details
As a solution I ended up using the Scythe Mini-Kaze Ultra (SY124020L) times three. These fans put out 5 CFM @ 20 dBA. That will cut the noise output by roughly 40% while maintaining half the stock airflow. As a word of warning consider the environment you are placing this switch into. I would not recommend placing this switch into a very warm or hot area after modifying the fan configuration. Nor would I swap the fans if you intend on fully utilizing the port capacity with moderate or greater traffic. Keep in mind it was built to the original specification for a reason. I only modified my switch because I don’t intend to push it to the outer limits of its capabilities. This process should work for the Netgear 24-Port GS724T too, which has just one fan to deal with.
If you stray from the Scythe model I selected be sure to take into consideration the power header. The Netgear uses a standard two-post power header block and the Scythe fans match up nicely. Make sure you unplug the switch before starting and avoid the power supply. This will obviously void your warranty. You’ve been warned. Now that I got the PC (the political kind) crap out of the way we can move on to the good stuff, like my latest video depicting the full process.
Required Tools/Items:
- Micro Screw Driver Kit
- PC Tweezers
- Three Scythe Mini Kaze 40x40x20 (SY124020L)
- Four Machine Flat Slotted Screws with Nuts (4-40 x 1) – Acquired from Lowes/Home Depot
Fan Specification Comparison:
Factory – Delta Product Groups – 40x20mm, 9000 RPM, 10.1 CFM, 33 dBA / 40x10mm, 8000 RPM, 9.5 CFM, 38 dBA (Model: EFB0412VHD / EFB0412VHA)
Swap – Scythe Mini Kaze – 40x20mm, 3500 RPM, 4.9 CFM, 19 dBA (Model: SY124020L)
How-To Video
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Iometer Tutorial and Introduction
Iometer – IO Benchmark and Troubleshooting Tool
When I started work as an IT professional I remember chasing my tail quite frequently. I would click and click until I was blue in the face. When that didn’t work I would venture out into the jungle that was internet. Of course these trips were perilous and infrequently yielded results worth the effort. The early days of internet were not exactly known for their efficient search engines. Learning how to travel down the road of effective troubleshooting can be a journey in and of itself. So that brings us back to the old adage, “Use the right tool for the right job.” One of these tools I have come to love is Iometer. On initial download and install it appears confusing and clunky to the eager user, but with the right guide this can be a trip of wonderment and intrigue.
Download and Install
The latest release of Iometer can be downloaded from iometer.org. Version 2006.07.27 is the latest non-beta release. A newer beta release can be obtained from sourceforge.net. If you want to download the manual, pop some popcorn and kick off your finest Mozart tunes. It’s a tad lengthy and a bit dry but very informative. Once you get Iometer installed on your system, fire it up. You will notice a DOS command window spawning separately. Note: If you are running Windows Vista or Windows 7 be aware you will be required to run Iometer as “Administrator”. The background window is the Dynamo process executed independent of the Iometer GUI process.
Iometer is the controlling program. Using Iometer’s graphical user interface, you configure the workload, set operating parameters, and start and stop tests. Iometer tells Dynamo what to do, collects the resulting data, and summarizes the results in output files. Only one copy of Iometer should be running at a time; it is typically run on the server machine.
Dynamo is the workload generator. It has no user interface. At Iometer’s command, Dynamo performs I/O operations and records performance information, then returns the data to Iometer. There can be more than one copy of Dynamo running at a time; typically one copy runs on the server machine and one additional copy runs on each client machine.
Topology Panel
When Iometer starts up you should see the “Topology” panel on the left listing your host as a manager. Iometer should automatically create a worker (thread) for every CPU (core) on your system. If for some reason it fails to create any workers under the manager, make sure you started Iometer as “Administrator”. Otherwise create a worker manually by selecting your manager (hostname), and clicking on the “Start a new disk worker…” icon. For our walkthough we will only be testing against one worker. Select your newly created or preexisting worker and proceed to the next step.
Disk Targets
Select the physical disk where you wish to perform the IO testing. You will notice a red line striking through the disk icon. This indicates a missing test file, so Iometer will automatically create the file on first run. Consider the amount of RAM in use on your system. It is recommended you create the largest possible file for testing to avoid caching your Iometer test file in RAM. I try to keep my memory at 10% of the Iometer test file. I have 8GB of RAM so I would create an 80GB file. To accomplish this you multiply 80 * 1024 * 1024 * 1024 \ 512. That gives us 167,772,160 sectors, or 80GB. One sector is 512 K. The full calculation is 80GB * 1024 = 81,920 MB * 1024 = 83,886,080 KB * 1024 = 85,899,345,920K / 512 K = 167,772,160 sectors. I know, I’m over-complicating it. Just multiply the size of the test file (in GB) * 2,097,152 to get the number of sectors for Iometer. Start “# of Outstanding I/Os” at 1 for now.
Access Specifications
Here you assign a series of targeted tests that get executed in sequential order under the “Assigned Access Specifications” panel. You have quite a bit of freedom and flexibility here to pull from preexisting IO scenarios or define your own custom access pattern. For this lesson we will just assign the “4K; 100% Read; 0% Random” specification by selecting it and clicking the “Add” button. This scenario is self-explanatory, and is generally useful for generating a tremendous amount of IO since your read pattern is optimal and the blocks are small.
Results Display
Moving along, we arrive at the “Results Display” tab. The purpose of this tab is to display your test results real-time once the test is executed. I leave the radio button for “Results Since” set to “Start of Test” as it averages the results as they roll in. I set “Update Frequency” to 2 or 3 seconds. Be careful about setting it too low as it is possible to affect the test negatively if it is borrowing CPU cycles to keep Iometer updated. While running you will see activity in the “Display” panel at the frequency you set. The three most important indicators are “Total I/Os per Second”, “Total MBs per Second”, and “Average I/O Response Time (ms)”. Total I/Os indicate the current number of operations occurring against your storage target. MBs per Second is a function of <I/Os> * <block size>. This indicates the amount of data your storage target is reading per second. One thing is for certain, that you don’t want to see any errors. You have another serious issue if that is what you are seeing.
Test Setup
The “Test Description” is used as an identifier in the output report if you select that option. “Run Time” is something you can play with. There are no strict rules regulating this setting. Generally speaking, the longer you run your test the more accurate your results. You system is expected to hicup, slow start, incur external requests and things of that sort. So extending your test a bit will level those bumps out. If it is a production test run it for 20 – 60 minutes. “Ramp Up Time” is a useful setting as it allows the disks to spin up and level out the internal cache for a more consistent test result. Set this between 10 seconds and 1 minute. “Record Results” is used when you would like to produce a test report following the test. Set it to “None” if you only wish to view the real-time results. You can accept the defaults for “Number of Workers to Spawn Automatically”. “Cycling Options” gives one the choice to increment Workers, Targets, and Outstanding I/Os while testing. This is useful in situations where you are uncertain how multiple CPU threads, multiple storage targets, and queue depth effect outcome. I encourage you to experiment with these parameters, especially the Outstanding I/Os (Queue Depth). Sometimes this is OS dependent and other times it is hardware related. Remember you can set the “Outstanding I/Os” under the “Disk Targets” tab. For this lesson we are going to take the default.
Test Run
Moving back to the “Results Display” tab, ensure you are not running any unnecessary applications or background jobs that may be consuming disk I/O. If you are running Windows Vista/7 you can pull up the “Resource Manager” (Task Manager -> Performance Tab -> Resource Monitor button) and view disk activity to validate the timing of your test run. Now that everything is ready, click the Green Flag button at the top to start the test. Following the Ramp Up time (indicated in the status bar) you will begin to see disk activity. Enjoy!
Video Walkthrough
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Incredible Free Video Knowledge Bank
So I was watching a piece by John Stossel the other day on Education in America and he spotlighted this guy that had a simple but amazing idea. He linked up his ability to create fun effective educational lessons with a free internet video service (YouTube). The end result was funding from Bill Gates and a repository of over 1800 short lessons on almost everything mankind has learned in the last 1000 years. Okay, maybe not everything, but it’s wildly impressive.
Here are the topics he covers:
- Algebra
- American Civics
- Arithmetic
- Banking and Money
- Biology
- Brain Teasers
- Calculus
- Chemistry
- Competition Math
- Computer Science
- Cosmology and Astronomy
- Credit Crisis
- Currency
- Current Economics
- Developmental Math
- Differential Equations
- Finance
- Geometry
- History
- Linear Algebra
- Organic Chemistry
- Paulson Bailout
- Physics
- Pre-Algebra
- Pre-Calculus
- Probability
- SAT Preparation
- Singapore Math
- Statistics
- Trigonometry
- Valuation and Investing
- Venture Capital and Capital Markets
It’s like that scene from The Matrix where Neo jacks into the loading program for the first time and Tank starts loading his brain with instant knowledge on demand. At least that’s how I’m looking at it anyway. The website is called KhanAcademy.org. I plan on making an effort to watch at least one video a day. My brain already hurts, I might as well go for bust.
Here is an example video under the Computer Science section. Ah yes, Fun With Strings, good stuff.
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How To Build a Custom SAN (Storage Area Network)
Hardware, Part 1
Why I Wanted to Roll My Own SAN
In my constant search to find the perfect SAN (Storage Area Network) I came to the realization a long time ago that it really doesn’t exist. Now of course the perfect SAN would be described differently depending on who you talk to and what the SAN is going to be used for. I wanted a SAN for the purpose of doing just about anything. That would mean I needed the SAN to be highly flexible in all possible aspects while keeping it practical and affordable since I’m working from a hobby budget, at least in my case. Given the current economic conditions that exist for most small business these days wasteful spending is not really an option if you are considering a SAN build for your company or employer.
After searching high and low for a black-box SAN solution I came up disappointed every time. Whether it was USB capable only or relied too heavily on RAID based software I really couldn’t find anything that perfectly fit my wishful-thinking requirements. My goal was to find a SAN with the following features.
Home / Small Business SAN Requirements:
- Cheap
- Nobody likes spending their own cash
- SAN solutions are already too expensive
- This market is ripe for innovation
- Hot-Swap Configuration
- Improves uptime by avoiding system shutdown to replace hardware
- Takes advantage of SATA hot-swap specification
- Small Form-Factor
- You can have your cake and eat it too. Large storage in a small space is always fashionable.
- Quiet
- In case you sleep next to it
- Low Power Consumption
- Because hibernating a SAN gets people fired
- If the SAN is going to be used infrequently, little is gained by burning through the watts
- Hardware RAID
- Personal preference on this one as the great debate between hardware/software RAID rages on
- Prefer the audible alarm signaling drive failure and error LED on drive bay (Software method less obvious)
- Dependable IO Controller
- 10+ SATA II Ports to match the 10 hot-swap drive bays
- Quality controllers will provide vast performance improvements over cheap boards
- Features like Staggered Spin-Up, Out-of-Band managements, and Audio/Visual Alarms
- RAID-5,6
- Your requirements may dictate RAID 10,50 etc..
- Are you looking for speed, safety, or both?
- Dependable 1Gb NIC Port
- Intel and Broadcom are two industry standards compliant and reliable manufacturers
- Avoid bottleneck by using a fast 1Gbps+ connection
- 1Gb connectivity minimum if using iSCSI or NFS
- 110MB Transfer Rate (WD10EARS) equates to 880Mbps. Add RAID and you are over 1Gbps
- Bootable USB Port
- Handy when you don’t have room for a CDROM and need to load the SAN OS or additional software
- On-board Video Card
- Reduce costs
- Improve airflow
- Improve simplicity
- Ventilated Case
- Hard drives are going to generate heat. A cool system is a happy system.
- Power Supply
- Capable PSU supporting 12+ HDs, MB, and CPU
- SAN Operating System
- Slick interface that makes quick effective work of slicing up your storage as you desire
- Protocols: iSCSI, NFS, CIFS/SMB, FTP (everything else would be icing on the cake)
- Upgradable Software and Hardware
- Something new and fresh is always on the horizon
- Don’t drop a ton of money on an entirely new all-in-one SAN every time some new feature comes out. Just upgrade as you need. Vendors love you a lot more if you buy a new SAN to get the latest do-dad.
From my list of requirements I was already thinking this task was going to be tricky trying to track down a “Ready-to-Run” black box SAN. I started looking at solutions like using a Drobo, but it fell short on several key areas. So I turned to direct attached storage (DAS) in the form of eSATA, but they were not network accessible. It just seemed like the market for high-end SAN feature with a low end budget was non-existent. That was unacceptable to me in the end and I was determined to come up with something feasible. I knew it could be done, and for some reason the industry has always seemed to lag behind in the storage market for the prosumer techie like me. Time to roll up my sleeves and make it happened the good old fashioned way. It was time to Do It Yourself!
So I rolled up my sleeves and started researching components for my home made SAN. After all I was only going to use it as my backup server, VMware Host, Oracle Database Block Storage, media streaming server, home file server, and raw video data store. I just wanted to be prepared in case anything else came up. My search started with finding a good RAID enclosure, so I could see visual indicators of drive activity, hot swap failed drives, and squeeze 5 3.5″ drives into 3 case bays with the enclosure. I considered the RAID enclosure and the RAID Controller the two core important pieces of hardware I really wanted to get right the first time.
The Build
I jumped right in to researching the enclosure. I looked at so many different enclosures and the majority of these enclouses had one commonality between them. They were all cheaply constructed and of poor quality. None of them rated all that well and bothered me quite a bit as this was the keystone in my build. Right off the bat I was mildly discouraged in my quest for greatness. After stepping back and thinking about it a while I realized the majority of entry level business SANs were using Supermicro components for their SAN solutions. So I stopped beating myself over the head with a power dongle and went straight to the source. I found the Supermicro CSE-M35T-1B. In the end I was quite pleased with this purchase, especially the quality all things considered.
Next on my list was the all important RAID controller. My searching lead me to an Areca ARC-1260 (I picked up one used, and this model is no longer produced) for their good reviews, very capable controllers and useful out-of-band web user interface for monitoring and managing the hardware aspect of the RAID configuration. This would avoid rebooting your storage area network to check a configuration, tweak a setting, or swap a failing drive. That would kind of defeat the purpose of using a SAN.
Next I wanted to find a solid motherboard. Since I was quite happy with the purchase of my two Supermicro RAID enclosures I thought a Supermicro motherboard deserved consideration. In my requirements I stated on-board video and non-generic network port so this was a logical choice. I was able to hunt one down, although I admit at the time it was hard to find a single socket, embedded video, and built-in RAID controller. My strategy here was to locate my operating system hard drives away from the primary RAID controller. I didn’t want to create a single point of failure or controller bottleneck. This would allow for expanded flexibility too. So I configured two 250GB drives using RAID 1 attached to the Supermicro on-board RAID controller to protect against loosing my SAN operating system and RAID configuration. I also wanted to avoid co-locating the SAN OS drives with the hot swap production drives. I didn’t even want to take the risk of accidentally pulling an OS drive from the RAID cage.
Next up I had to find a home for all this beautiful hardware to reside. I was looking for something convenient to work with internally, had plenty of ventilation, fairly quiet, plenty of bays for stacking two RAID enclosures that would consume six bays, and a sleek black box feel. I’ve owned Lian Li cases in the past and found what I was looking for. I particually liked this case because there was no unnecessary wasted real-estate on the front of the case, just nine 3.5″ bays oriented from top to bottom with a very clean look. This prevented from from purchasing a server town in turn keeping prices down and size to a minimum. Check, check and check!
A few other items will be needed to complete your build. Don’t forget to purchase memory, a power supply unit (PSU), and the processor. For the power supply you will want to take the standard items into account along with the total number of hard drives you plan to ever use with the system. For example the average 3.5 SATA2 disk may consume 30W on spin-up. Today’s larger SATA disks consume a lot less power because of the larger cashes and combined algorithms to reduce drive head activity. If you go with a green drive like I did you are now looking at 5-7W with read-write activity and half that at idle speeds. If you select a higher end RAID controller you should have the option of using a “Staggered Drive Spin-Up”. This will help offset the power demand on boot. I selected a 600W PSU for my particular build. With both RAID cages fully loaded you would have 12 drives spinning. This will leave you with plenty of room for growth. For the RAM I used two 1Gb sticks of dual channel. Before you load your system up with RAM check the documentation for your SAN software to determine how it utilizes the memory. If it employes a caching strategy using your system RAM it would definitely be worthwhile to load your system up if performance is what you seek. I will discuss this in further detail in my second article discussing how I used Openfiler as my SAN operating system. For the CPU I happened to have a 2.2Ghz processor laying around, so I just dropped that into the motherboard. You really don’t need anything special as far is the CPU is concerned. Your critical hardware will always be the IO controller. Now iSCSI may tap some of your CPU to handle the added processing in the event you don’t have a TOE (TCP/IP Offload Engine) capable NIC. Again this is assuming you are even using iSCSI.
Everything is Assembled, Now What?
Okay, you have your newly assembled dream SAN sitting in front of you and you can’t find a power receptacle fast enough. Plug everything up, preferably though en UPS (uninterrupted power supply) after spending all that money and time. Hit the power switch and cross both fingers you avoid angering the hardware gods and having the beeps of doom unleashed upon your home or happy work place. If all goes as planned you should be walking through the BIOS configuration. Don’t forget to configure your two locally attached hard drives as RAID1 in preparation of the SAN operating system install. Save, reset, and configure your RAID adapter with the second boot. Like I said before, are you looking for speed or safety? I went with RAID5 for the time being. If I had 10 drives installed I would probably go with RAID6. At this point you are starting to realize that the sun will soon be rising after your perilous journey through Mordor, and you start to taste the deliciousness of a gummy bear dipped in peanut butter victory. Now comes the part where you select a SAN operating system for your new robot. There are two obvious choices in my mind: Openfiler and FreeNAS. I will be profiling Openfiler in a followup article. I selected it for a number of different reasons, all of which I will cover. For now kick back, and pat yourself on the back by taking a Forza victory lap on your XBox360. Even better if you are doing this at work. Don’t forget the pizza poppers as they are standard geek and gamer food.
Video Walkthrough
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iTechStorm First Boot
Welcome to iTechStorm where the technology of new and old gets a fresh coat of paint and visitors are welcome to contribute to the digital storm of ideas. This is the first of many posts where I will cover various technologies like VMware, iSCSI, block storage, SANs, benchmarking, networking, Oracle, and configuration examples to name a few things. Content ideas will always be welcome.
