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By William Van Winkle |
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Inevitably, many clients will want more storage, if only for near-line storage and backup. Blades are not like normal rackmount servers in that there are no PCI Express or PCI-X slots sitting around waiting to take an additional storage controller. The blade manufacturer has to design a plug-in module for the backplane that links the blade enclosure to external storage resources. In Supermicro’s case, the OfficeBlade offers two module options: one 20 Gb/s double data rate (DDR) InfiniBand switch and up to two Gigabit Ethernet switches (2 Gb/s aggregated) or pass-through modules. (You’d pick the pass-through module if the client already had an existing switch in operation.) In the first quarter of 2008, Supermicro will follow up with a 10 Gigabit Ethernet module. Small businesses may not be as familiar with InfiniBand, but medium-sized operations are more likely to employ the scalable switched fabric technology either for attaching external storage or linking multiple blade enclosures. InfiniBand is the modern interconnect of choice for high performance computing (HPC) systems, so keep this module option in mind as you approach academic and research accounts. The last component OfficeBlade accepts is the chassis management module. This is the piece that allows for remote control over practically everything within the blade enclosure—-server blades, cooling fans, power supplies, LAN switches, etc. This control is enabled through the 2.0 version of Intelligent Platform Management Interface (IPMI), an industry spec championed by Intel and now backed by over 150 vendors. The original intent for IPMI was to be a monitoring tool. Console operators can keep an eye on variables such as fan speeds, voltages, temperatures, and power supply status. In the latter two versions of IPMI (oddly, version 2.0 is actually the third version), not only was remote monitoring enabled but also control over things such as server resetting and rebooting. Fueled by IPMI 2.0, Supermicro’s CMM provides features like KVM over LAN and KVM over IP. With this, admins can use any remote system running the CMM console app to control any blade in the enclosure, just as if the user had a KVM switch physically hooked into each blade. The control module’s Virtual Media over LAN function supports drive redirection and emulates a USB floppy/CD drive. Without this, you wouldn’t be able to perform a remote software installation onto a blade node. The CMM supports extensive alerting and logging features and is totally OS-agnostic. Buyers wanting the utmost in uptime assurance should consider installing a second, redundant CMM.
Also note that Supermicro’s OfficeBlade chassis is CPU-agnostic. Users can have Xeon-based blades running adjacent to their Opteron counterparts. For buyers who aren’t married to a particular CPU brand, this can be a tremendous advantage that allows them to buy whichever technology happens to be best for their operating systems, applications, or other needs at the moment. INTEL’S MODULAR SERVER If we skipped straight to the punch line and told you what the Intel Modular Server with Multi-Flex Technology is, it might downplay the significance of the product and the three and a half years of R&D that preceded it. Intel knew that someday blade architecture was going to make sense in the SMB world. The total cost of ownership benefits were simply too strong not to help smaller businesses as well as enterprises. The question was how to deliver equivalent ROI to these smaller operations while scaling down the end-to-end price. “The whole idea behind the Modular Server was around saving money,” says Intel’s Jared Leavitt. “How do you take the cost out of server hardware? As I and my team went out and did research, we went to small and medium businesses and asked them about their problems. It’s not like the enterprise where you’ve got TCO and efficiency teams. These guys have $100 to stretch as far as it can go. So cost is a really big priority with SMBs, and so are flexibility and ease of use.” If we only look at the blade modules, we find fairly standard fare. (Intel prefers to call its blade nodes “server compute modules,” perhaps in part to distance the units from the stigma of “enterprise blades,” but there’s also a technical reason we’ll explore in a moment.) As of the present launch here in January, each node’s motherboard features Intel’s dual-processor 5000P server chipset, which was the heart of the Bensley platform. While the 5100 and 5400 chipsets are newer, the 5100 is limited to DDR2 memory and the 5400 is billed as a workstation product. The 5000P accepts up to eight physical rows of FB-DIMMs and is compatible with both quad-core and 45nm (Penryn) technologies. In reality, the only notable thing that the 5000P can’t do is support a 1600 MHz front side bus. So while the Modular Server’s nodes will work with any modern Xeon processor, the latest 1600 MHz FSB chips would be throttled back to 1333 MHz.
As with Supermicro’s OfficeBlade, Intel here includes a chassis management module with the Modular Server. What struck us as exceptional is the Virtual Presence Modular Server Control software that connects the console client to the management module. We had an opportunity to dive into a back room at Intel and see the management GUI first-hand. Compared to the command line prompts that historically dominated blades, Intel’s new interface is ridiculously intuitive. Virtual Presence shows exactly what the front and back of the Modular Server unit look like. If there are only three nodes installed, you see three nodes in the Virtual Presence chassis, with the remaining slots showing as black. On the rear view, you might see three power supplies installed and one blank plate. The Dashboard view shows overall system health at a glance. Naturally, easy tools are presented for out-of-band remote management and discovery. The config we observed was running two nodes, two power supplies, and six hard drives. A power graph in the Dashboard showed the total system load at 348W, resting comfortably in the green section of the power bar graph. Registering in the green section means the system has redundant power available. The yellow section says that power draw is now heavy enough to eliminate redundancy; all PSUs are being utilized. The red section indicates overload and that system components are either being throttled back or shut down. All in all, the GUI is simple but remarkably powerful. “A reseller can say, ‘Hey, I’ll service your box whenever and only charge you a very modest fee,’” notes Leavitt. “If something goes down, they can pull up the Control GUI and manage it remotely. They can send out their high school intern to do the truck roll. Say there’s a hard drive or power supply or even a compute node that went bad. Give it to Johnny, he runs down there, and physically replaces it. He doesn’t have to be an IT guy or even know anything about it. The reseller can remotely turn on a light on the chassis that shows him which piece to pull out. Johnny just swaps and walks away.” The front of the Modular Server chassis features 14 hot-swappable 2.5” drive bays. Intel bills these as being for SAS drives, although we all know that SAS controllers usually run SATA drives without any problem, and Intel’s modular controller is no exception. You can use 2.5” SATA drives. Intel quietly dissuades against this option—-officially, SATA drives are not supported—-because of component reliability issues. Mobile drives are not designed for 24x7 operation or rigorous vibration control; enterprise drives are. Unfortunately, there are no true 2.5” enterprise SATA drives on the market today, so until that happens, Intel is sticking solely with SAS.
Note that the drive bays are built into the Modular Server chassis, not the server nodes. This is critical. This is the secret sauce behind this product. The drives direct connect into the chassis midplane, which in turn connects to the system’s optionally hot-swappable and redundant storage module(s). These handle the system’s RAID functionality. There are several SAS expanders in the system, although they are located on the drive interposer, not in the controller module. The reason why it’s important for the drives not to be built into the server nodes is that you now have complete separation between the compute and storage sides of the server collection. This has several important ramifications. Probably first among these is that you no longer have 10 separate pools of storage, as you do with the OfficeBlade. Rather, you have a unified storage area network (SAN). SANs are immensely advantageous because they enable block-level data access, critical for highly transactional databases. The two primary architectures behind most of today’s SANs are Fibre Channel or iSCSI over Ethernet. Because iSCSI is essentially SCSI running via TCP/IP packets, the technology tends to be very CPU-intensive. Alternatively, Fibre Channel remains inordinately expensive and very complex to set up. Intel’s Leavitt quips that Fibre manuals look like phone books.
Businesses have increasingly tolerated these downsides for the flexibility benefits offered by SANs. With SANs, admins can create virtualized drive volumes from physical drives located anywhere from the same chassis to opposite sides of the country, and the volumes register to the user as local drives, right down to any supported RAID level you please. SANs also allow for diskless booting, meaning that the compute nodes no longer need resident, attached drives to boot from. A system can boot from a drive volume located anywhere, which makes uptime and maintenance far more favorable. This separation of compute and storage has typically been reserved for wealthy enterprises and some medium-sized operations. Intel’s Modular Server is the first machine we’ve seen that effectively delivers a “SAN in a box” straight off the shelf. Why hasn’t someone done this before? According to Intel product marketing engineer Bryan Young, the solution may look simple on the outside, but, again, it took over three years to develop. Moreover, SAS switches only arrived on the market this year and are still in scarce supply. Each Modular Server node’s motherboard has a SAS controller on it with dual 3 Gb/s pipes to the storage controller. Only one controller is needed. (The redundant spare controller doesn’t actually start shipping until later in Q1.) With Fibre Channel, the storage connections are typically 2 Gb/s, and the fastest is 4 Gb/s. SAS lands right in the middle, so if you’re new to the technology, realize that it offers true, enterprise-class throughput.
Looking at other blades, it might well seem that the Modular Server’s storage is insufficient. There are only 14 drive bays compared to the OfficeBlade’s 60, after all. (Soon, Intel will have a different SKU featuring six 3.5” drive bays rather than today’s 14 2.5” drives.) Obviously, the merits of each approach are relative. When a user needs to expand capacity beyond the six drives tied to each blade, he has to resort to either Fibre Channel or Ethernet iSCSI, both of which have their drawbacks. With the Modular Server, he would simply use that external x4 connector to link to an adjacent RBOD enclosure on the rack. (JBODs should work, but Intel is not officially supporting them.) While 12-drive SAS JBOD enclosures start in the $1,000 to $2,000 range, a 12-drive Fibre Channel box-—almost guaranteed to feature integrated RAID processing—begins in the $4,000 range. “One Fibre Channel switch is extraordinarily expensive, even at the low end,” says Intel’s Leavitt. “It’s more expensive than my box only half-loaded. So your cost is just way out of control. Even if you just go buy an iSCSI SAN box, the cheapest thing on the market, you’re paying three to five grand for just that. Then it’s going to take at least a week to hook the thing up. With ours, it’s plug and play.”
SAS is more affordable, simpler, and literally makes adding more storage to the base server enclosure a snap. External drives show up as just more storage capacity in the total storage pool. In the Modular Server Control GUI, you can jump into the Storage Configuration window, arbitrarily select the amount of capacity you want carved out for each virtual drive, and apply the type of RAID protection desired for each drive. Out of the box, setting up a couple of virtual SAN drives using traditional approaches might take days. With the Modular Server, it takes just a few minutes. The hardest part is mounting the drives in their carriers. The rest boils down to only a few GUI clicks. ...more |
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