Electronic Design

EiED Online>> Building A SAS RAID File Server

System builders often have an edge when it comes to servers, especially when they can take advantage of custom cases for delivering RAID server solutions. Adaptec’s 335SAS enclosure changes the equation by providing a professional RAID system in a compact package. It fits four hard disk drives and a slimline optical drive in the space normally used by three 5.25-inch drive bays. Couple it with Adaptec’s 4805SAS PCI Express RAID adapter and you have the best RAID platform available at this point in time.

Of course, a high-performance RAID system needs a matching compute engine to get the most out of the server. This is where ASUS’s K89N-LR motherboard comes into play. It has a PCI Express slot that will handle the 4805SAS plus PCI-X and PCI slots in case you need more than just the gigabit Ethernet support built into the motherboard. The motherboard can handle an Opteron or Socket 939 Athlon 64. We made use of AMD’s FX-60 dual-core Athlon 64, making this a dual-processor system in a single socket.

The motherboard supports up to a four-drive RAID system, but it can’t hold a candle to the 4805SAS. The latter can handle up to eight drives, although we only take advantage of four at this point. It also supports more advanced RAID configurations in addition to high-performance SAS (serial attached SCSI) drives like the four 15k rpm, 73-Gbyte Seagate Cheetah 15K.4 SAS drives that will be housed in the Adaptec enclosure. SAS drives are faster and more reliable than the SATA drives typically found in low-end servers. This system may be at the low end in terms of cost, but not in terms of performance.

Another twist in our system design is the backup mechanism. It turns out that the Antec server case we used has four external drive bays, so we have one extra bay after the Adaptec enclosure has been installed. We included a single removable drive enclosure from KingWin to house one of Seagate’s NL35 near line hard disks. These are often used for primary storage that does not need the performance of the Cheetah drives. In this case, we use it as a backup medium. The 500-Gbyte NL35 drive has more than enough space for multiple backups.

Alternatively, the NL35 can be used for its designed purpose, which is to provide a tiered storage solution. Critical, frequently used data that is kept on the Cheetah drives, and data that is less frequently accessed is placed on the NL35 drive. The Antec case has internal bays that could be used for multiple NL35 drives in a RAID configuration as well.

Setting up the system is a bit more involved than a typical server, which makes this project more interesting. The rest of this article covers the components in more detail, the installation of the motherboard in the case, configuration and installation of the Adaptec enclosure, and then the NL35 drive installation. We wrap up with the final configuration including installation of Microsoft’s Windows 2003 Server software. Linux is another viable alternative supported by the hardware, although I ran out of time before being able to check out this configuration.

The Components
Antec’s Titan case was a joy to work with. Its removable front bezel and snap-in mounting rails made installation of the drive enclosures a snap. The double hinge door open up to 270º, allowing the door to flip out of the way when accessing the drive bays. It is plastic so it does not provide high security, but servers should be kept in secure locations anyway. Front-panel access for USB, Firewire, and audio was handy, but we only took advantage of the USB ports.

The case has 10 drive bays. All four external 5.25-inch bays are used by the two enclosures. For this project we did not take advantage of the six internal 3.5-inch drive bays. The case has room for an extended ATX motherboard. This includes CEB specification motherboards. Our ASUS motherboard had no trouble fitting into the case. We only need to take advantage of one of the seven expansion slots, although there are a pair of PCI and a pair of PCI-X slots that can be used on the motherboard for additional peripherals.

The TruePower 2.0 550-W ATX12V v2.0 power supply was large enough to easily handle the full peripheral complement. The power supply has all the latest power connectors, including support for PCI Express and SATA hard drives. However, these were unnecessary for this project since we did not have a power-hungry PCI Express adapter. Likewise, the SAS drives were behind enclosures that use the standard four-pin drive power connectors. The case had a rear 120-mm standard fan with a TriCool 3-speed switch, and there is space for a pair of 92-mm fans in front.

The ASUS K89N-LR motherboard is based on NVidia’s nForce 4SLI chipset. It supports a single Opteron or Socket 939 Athlon 64. It also supports dual-core chips like the AMD FX-60 dual-core Athlon 64 that we used in the project. The motherboard has a pair of Broadcom 1-Gbit Ethernet interfaces eliminating the need for network expansion cards. The NVidia built-in display obviates the need for a PCI-X or PCI display adapter especially since we needed the x16 PCI Express slot for the x8 Adaptec SAS RAID controller. The motherboard has two PCI slots and two PCI-X slots that can be used for expansion.

The motherboard has the usual complement of serial, parallel, and PS/2 ports. It has a pair of USB ports on the rear and eight internal. A pair of the internal ones are used for the case’s front panel and the rest can be connected to adapters that take up unused slots on the rear. The motherboard also supports optional BMC and mini-PCI boards.

The dual 133-MHz Ultra DMA IDE controllers are useful, but we only needed one for the slimline DVD writer. The heavy lifting was done by one of the four SATA-II interfaces and the Adaptec SAS controller. The SATA-II interfaces run at 3 Gbits/s. That is on par with SAS speeds, so the NL35 is not poking along. The motherboard supports RAID 0, 1, 1+0, 5, and JBOD configurations. It could, in theory, be used with the Adaptec enclosure although this configuration would use up all the on-board interfaces.

AMD’s FX-60 dual-core Athlon 64 is blazingly fast. It supports larger caches than the typical Athlon 64 and is on par or better than most Opterons. The on-chip memory controller handles dual-channel transfers for even better performance. All the better to feed the two processor cores. Each core has its own L2 cache. Multiple cores are especially important on servers that run a wide range of services simultaneously. Unlike a desktop PC, a server will easily keep both cores running. If you don’t need the performance you can always start with a lower cost, single-core Socket 939 Athlon 64.

The ASUS K89N-LR motherboard supports up to four dual-channel 184-pin 400-MHz DDR memory modules. We used a pair of the 1-Gbyte Platinum memory modules from OCZ Technology (see “Memory: OCZ Technology Platinum Dual-Channel Kit,” ED Online 11719). We had great luck with these in our Best PC of 2005 as well. The system supports up to 4 Gbytes of memory. And these days, pumping the memory to the max is quite common.

Adaptec’s 335SAS enclosure ($369) shows what inventive engineers can do. It packs four hard drives into the space normally allocated for three and still has room to include a slimline optical drive. RAID systems can be constructed with just a pair of drives but things don’t get interesting until you have at least four. Our case only accommodates one 335SAS enclosure, but others are available that trade the internal drive bays for more external drive bays. In this case, a pair of enclosures can be used. The matching 4805SAS RAID controller can handle two enclosures. The clean design of the 335SAS enclosure will become more apparent later in this article.

The 3/4-length 4805SAS RAID controller ($995) is definitely for heavy lifting. It supports RAID 0, 1, 5, 10, 50, and JBOD as well as the Adaptec Advanced Data Protection Suite with RAID 1E, 5EE (hot spare), 6, 60, Copyback Hot Spare, and optional snapshot backup. RAID 6 and 60 provide dual drive failure protection. The controller has 128 Mbytes of ECC-protected DDR DRAM. A battery unit is optional.

The 4805SAS RAID controller supports up to eight 3-Gbit/s SAS or SATA-II drives. It has a pair of special 4-drive internal connectors and a single 4-drive external connector. The 4805SAS RAID and 335SAS enclosure come with a matching cable so you don’t have to play with four individual cables. The cable also has a locking mechanism not found on the hard-drive connections.

The controller requires an 8x PCI Express slot. It supports both AMD and Intel 64-bit processors. It comes with a copy of the Adaptec Storage Manager, but more on that later. The controller’s BIOS handles system configuration transparent to the operating system and provides feedback via the Adaptec Storage Manager.

The Kingwin KF-813-BK SAS/SATA enclosure is more conventional and what you would typically find in a RAID-based server. It is large, but it suits our purpose of holding a fifth hard drive for backup purposes. The enclosure has three fans: two in front in the removable tray and one rear fan. Unlike the Adaptec enclosure, the Kingwin uses a 64-pin DIN connector for the hot swap mating connection. It has a SAS/SATA cable interface internally and externally. It also requires a key to remove the drive.

Seagate provided the primary and backup hard drives. The primary RAID system consists of four 15k rpm 73-Gbyte Seagate Cheetah 15K.4 SAS drives. These are also available in 146- and 36-Gbyte capacities. The have an average read time of 3.3 ms and an average write seek time of 3.8 ms. The SAS drives have a 96-Mbytes/s sustained transfer rate. MTBF is rated at 1.4 million hours full duty cycle. Versions are also available for Ultra320 SCSI and Fibre Channel. These SAS drives are likely to be the most popular. The drives come with a 5 year warranty.

The Seagate NL35 SATA-II drives are available in 250-Gbyte, 400-Gbyte, and 500-Gbyte configurations. We had one of the 500-Gbyte units. They have a 3-Gbit/s interface and support native command queuing. The NL35 drives rotate at 7.2k rpm, almost half the speed of the Cheetahs. Corresponding specs are lower as expected. The NL35 transfer rate is 65 Mbytes/s and seek times are on the order of 8 to 9.5 ms. The drives are quiet (2.8 bels) and they also come with a 5 year warranty.

Servers typically run headless, but it is much easier to set up a system with a monitor attached. We took advantage of Viewsonic’s 19-inch VX924 LCD display (see “Display: Viewsonic VX924 19-inch LCD,” ED Online 11722) from our Best PC of 2005. This is definitely overkill for a server, but it looks so nice with its matching black and silver trim. The display has ultra-high brightness (270-nit brightness) and contrast (550:1 contrast ratio) for those late nights when diagnosing problems on the network. The other advantage of the VX924 is the large 1280-by-1024 screen size that is handy when managing the server. More screen real estate is always better.

Another favorite used on the system is Logitech’s MX5000 keyboard and mouse (see “Keyboard and Mouse: Logitech MX 5000,” ED Online 11726). This Bluetooth wireless system is very handy since it can be easily hidden when not in use. It is also easy to remove and install when switching the system between headless mode. The Bluetooth security matches the keyboard and mouse to the system so someone down the hall does not inadvertently start typing on the server.

Case and Motherboard
The Antec Titan case comes apart easily and the side panels have spring-loaded screws that don’t get lost when you take the panels off. The front panel snaps off easily after releasing the side tabs, so don’t force it. It actually has a hinge that allows the panel stay on the case, but it is just as easy to remove or reinstall. I started by removing all the panels and the tabs that block the external drive bays.

The ASUS K89N-LR motherboard (see Fig. 1) was the next item to attack. I started by mounting the dual-core Athlon 64 CPU (see Fig. 2) into the ZIF (zero force insertion) socket. It is easier to install the chip before putting the motherboard into the case. Keep the motherboard and yourself grounded while working with the semiconductors. They are rather expensive and prone to destruction from static electricity.

The next step was to install the heatsink mounting bracket (see Fig. 3) that comes with the motherboard. Tighten the mounting screws but don’t break the motherboard. This bracket is what keeps the heatsink/fan unit in contact with the CPU. Smear on the heat-transfer paste or gel that comes with most heatsink/fan units. Some include a sticky pad that is placed on top of the CPU. All perform the same function, providing a good conduction path to the heatsink.

We also installed the pair of OCZ 1-Gbyte Platinum dual-channel DDR memory sticks in two of the four memory slots. 2 Gbytes is probably the minimum for a system of this caliber and 4 Gbytes would be even better. Don’t skimp on memory. It probably has one of the best paybacks of any component in the system for the money.

Before installing the motherboard in the case I added some small plastic feet on the back of motherboard (see Fig. 4). These feet came with the case and are needed because the case does not always have all the holes in the proper spots, as in this case. They were mounted on the side of the motherboard closest to the front where there is little pressure when inserting or removing adapter cards.

Finally, it was time to place the motherboard in the case. Don’t forget to install the backplate that comes with the motherboard or the connectors will not fit out the back. You also need to remove the paper from the plastic feet and press them down to fix them to the case. Make sure the rest of the screw holes match up with the mounting holes before doing so. You only get one chance. It is relatively easy to do, but it does take patience.

I then attached the power cables (see Fig. 5) and the power switch and the other front panel cables. The system was ready for its first test since it has the video adapter built into the system. I grabbed a standard USB keyboard for the initial test. I then plugged in the Viewsonic VX924 LCD display and powered up the system. The BIOS started right up and it was time move onto more interesting parts.

The Adaptec 335SAS Enclosure
The Adaptec 335SAS enclosure is a smart looking box (see Fig. 6). It has four hard disk drive trays on the bottom and a thin slot at the top for a slimline optical drive. Although the unit holds five drives, it is not as large as shown in this side view (see Fig. 7).

If you are going to use only the hard disk trays then you can skim the next few paragraphs because installation of the optical drive is a bit more involved and requires removal of the enclosure’s backplane.

Start by removing all the drive trays (see Fig. 8). Each tray has its own release button and handle. There are two status LEDs per tray as well, although we don’t have to worry about them here. To remove a tray press the release button, pull out the handle to release the drive, and then pull the entire tray out of the unit. Once this is done you can see the 335SAS enclosure’s backplane (see Fig. 9). This side of the backplane has the SAS sockets. The SAS sockets are designed for hot swapping and they should work with any standard SAS hard disk.

Next take a look at the back of the enclosure (see Fig. 10). There is the enclosure’s cooling fan and sockets for power and data. The fan is removed by squeezing it so the mounting tabs release. Also unplug its power cable from the backplane. Remove the three screws holding the back plate and slide to the side. This provides access to the backplane. Remove all the screws from the backplane and lift it out. Place it in an antistatic bag like the one the motherboard came in. The backplane and back plate will be replaced once the DVD writer is installed.

I used a slimline DVD writer drive from Logic Supply. There are two mounting rails and a slimline-to-IDE adapter bracket. All these come with the enclosure. These were mounted on the drive using the accompanying hardware (see Fig. 11). Be careful not to lose the screws as they are very small and hard to find at a typical hardware store. A short power cable, also provided with the enclosure, plugs into the adapter bracket. The other end will plug into the backplane after the drive is installed.

I slid the DVD writer into the enclosure after removing the slot cover on the front. The DVD writer locks in place. I then attached the IDE cable (see Fig. 12). Here is a hint: Find yourself a two-foot IDE cable. The one that comes with the enclosure is too short for this configuration and the one that comes with the motherboard is barely long enough to work. The IDE connector on the motherboard is as far away from the drive as you can get. A two-foot cable has a few inches of play and should not interfere with any adapter cards.

Make sure the power and IDE cables are coming out the back of the enclosure and then reinstall the backplane. There are small openings along the top so the power and IDE cables can easily fit. Do not try to pull the cables through with the backplane installed. You will likely break the backplane and/or cable. Plug the power cable into the backplane (see Fig. 13) and snake the IDE cable through the back plate. You can then install the back plate (see Fig. 14). The fan can be snapped back in and its power cable connected to the backplane.

Now comes the easy part.

The empty Adaptec trays look fragile without the drive installed (see Fig. 15). Once the Cheetah drives were installed, with the help of four screws, the tray is very solid but the electronics of the drive are exposed (see Fig. 16). This is the primary difference between this enclosure and the Kingwin enclosure used for the NL35 drives. The rear view of the tray and drive shows the SAS connector that handles power and data (see Fig. 17). SAS, and SATA, are point-to-point interfaces so there are no jumpers to contend with. Just keep in mind that you will need a safe place to put a drive when you remove it from the unit. Don’t set a cup of coffee on one.

Next install the Antec case drive slide brackets on each side of the enclosure. A pair will work, but it is better to use two pairs (see Fig. 18). The mounting screws come with the case.

The last thing is to install the RAID enclosure into the case (see Fig. 19). I found this to be a tight fit but workable. Removing the drive trays does not make any difference as the enclosure is quite rigid. The case slide brackets lock the enclosure into place. It will be difficult if you ever have to remove the enclosure. You might need an extra pair of hands so all four slide brackets can be released at one time.

The Kingwin SAS/SATA Enclosure
The Kingwin KF-813-BK SAS/SATA enclosure installation was similar to the Adaptec enclosure. With the exception of the optical-drive installation, it is almost as easy to install the Adaptec enclosure as it is to install the Kingwin single drive enclosure.

It is easy to see the difference between the Adaptec and Kingwin enclosures (see Fig. 20). The Kingwin enclosure is rigid but does not have a top or bottom because the drive tray does. Having both would be more costly and a bit redundant. The Kingwin enclosure has a small fan (see Fig. 21) at the rear. There are a pair in the tray as well. Note that enclosure has a conventional hard disk power connector instead of a SAS/SATA power connector.

The Kingwin tray is larger than the Adaptec tray, but it provides the disk with more protection. The connections are also different because the Kingwin does not use the SAS/SATA connectors between the tray and the enclosure. Instead, there are power and data cables inside the tray (see Fig. 22). The top cover has been removed in the photo.

It is a snug fit after plugging the NL35 drive into the tray’s cables and mounting the drive inside the tray (see Fig. 23). The Kingwin enclosure gets a pair of case drive sliders and then it can be installed in the case (see Fig. 24).

The front panel can be reinstalled once all the enclosures are in place (see Fig. 25). The front panel snaps into place only if all the enclosures are properly mounted.

Connecting up the System
It is now time to start wiring up the enclosures. The Adaptec enclosure uses a connector that differs from the standard SAS/SATA cable (see Fig. 26). The Adaptec cable handles four drives whereas a standard cable handles only one. Adaptec’s connector at both ends of the cable also has spring clips on the side for a more secure, locking connection.

One end of the Adaptec cable plugs into the Adaptec enclosure’s backplane (see Fig. 27). The cable is very long so connecting it to the motherboard is not a problem as the IDE cabling was. The other end of the cable plugs into one of the SAS controller’s internal connectors (see Fig. 28). Of course, it helps to have the SAS controller installed first. The only other thing to do with Adaptec’s enclosure is to attach a pair of power connectors to it. Use connectors on two different cables coming from the power supply.

The standard SATA cable that comes with the motherboard is used to connect the Kingwin enclosure to the motherboard (see Fig. 29). There are three additional SATA-II connections on the motherboard for future expansion. The Kingwin enclosure also needs a power cable connected to it.

Final System Check
I pulled all five hard drives before powering the system on. This let me check one subsystem or two subsystems at the same time. The BIOS recognized the DVD drive and the SAS controller. It was even able to boot the Windows installation CD, although I had to power down the system to install the hard drives.

The power up sequence was a bit more involved this time. The Adaptec BIOS allows the drives to be configured without the operating system. I set up the four Cheetah drives in a RAID 5 configuration.

I then installed Windows 2003 Server on both the RAID system and the NL35 disk. Only one would be used, but it provides a mechanism to easily recover the system from catastrophic failures.

Network managers have the favorite system configuration. Normally I boot from the RAID system. The RAID system is actually split into two partitions with the operating system and applications in one partition and data in the other. A nightly backup copies data to the NL35. I also have an image copy of the RAID operating system partition on the NL35. I tend to be a little paranoid, but I haven’t lost data in years.

The final system is shown here (see Fig. 30) with the Viewsonic VX924 LCD display and wireless MX5000 keyboard and mouse. It is running Windows 2003 Server with the Adaptec Storage Manager software running. The MX5000 keyboard was installed at the same time Windows 2003 Server was installed.

At this point it was time to have fun and start pulling drives, being careful to make sure the system had rebuilt a reinstalled drive before pulling a second drive. Adaptec’s Storage Manager tracked the changes. The Storage Manager can handle a cluster’s storage assuming it is hosted through Adaptec controllers. The controller actually handles rebuilding a replacement drive, but you can see the status using Adaptec’s software.

Overall, this project went very smoothly. The Adaptec documents were being updated, so I had a little help with the optical-drive installation.

Related Links

Advanced Micro Devices




Logic Supply



OCZ Technology



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