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by William Van Winkle |
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"Another thing that differentiates Netcell is that we use RAID 3," says Netcell's Don Clegg, vice president of marketing. "Essentially, this gives you RAID 0 performance with the protection of RAID 5. It synchronizes the hard drives and writes to all of them at once for high performance, and it uses a parity drive to give you backup protection. RAID 5 spreads the parity around. We keep a single drive that has parity, and since we know where that drive is, we're able to do parity calculations more quickly and we end up with better performance. RAID 3 can also spread, say, 64 bits evenly over four drives whereas RAID 5 will write to one drive, find parity, write to the next drive, and so on. RAID 3's method is called word striping, and it lets all the drives get written to at the same time, so write performance is roughly double that of a RAID 5." That said, the different RAIDs have different specialties. RAID 5 turns out to be a better performer when it comes to small files, and RAID 3 is better for larger files, especially media streaming, because it can't access multiple files simultaneously across the drives. On the other hand, when one drive in a RAID 5 fails, the array's performance gets cut in half. With a failure in a RAID 3, performance only drops by about two percent. If the parity drive fails, you simply rebuild it. If a data drive fails, you take the remaining drives, inject the parity into them, and recreate the data. The bandwidth loss is minimal because the Netcell chip is doing most of the work, and the processes run as background applications. In fact, the same is true when an array gets built in the first place. Unlike most RAIDs, which need to be built during an initial OS installation, Netcell's RAID 3 can be implemented on top of an existing configuration, which is why Netcell is so persuasive in Seagate's bundle. If you want to add a RAID without adding internal drives (for whatever reason), Netcell's chips can bridge internal and external drives into a single array. "Say you've already got your life on a drive," explains Clegg. "You don't want to have to reinstall just because you bought an add-on board. This is as simple as adding in the Netcell card, disconnecting the SATA cable from your old controller, plugging it into the new card, and adding either more drives or leaving it as is. It'll come up and recognize that boot device—which is a huge deal, because not many RAID controllers allow OS booting. At that point, it'll ask if you want to make a giant capacity volume, performance, mirroring, or mirroring plus performance. In three to four mouse clicks, you're migrating all of the old data to the new array. The migration might take hours to do, but you can continue to use the system while the migration happens in the background. And you can use a slider bar to raise or lower the priority of the migration process." Netcell also supports RAID 0, 1, and JBOD. Even though these configurations are commonly available from integrated motherboard RAID chips, going with the add-in card bestows all the system performance benefits of hardware-based RAID processing. RAID 5 is expected in subsequent releases, not because Netcell thinks people will prefer it but because it gets mentioned so often. Gamers and other enthusiasts will appreciate that Netcell does include a performance driver that can run as a System Tray icon and allow for ever faster performance than what the OS driver can provide. "This is a natural fit for this is anybody who has 1MB and above files on their system," says Clegg. "So pretty much all audio and video—enthusiasts, home users with digital cameras, and low-end workstation types. You don't even need three drives. With two drives, you can still do RAID 0 or 1 and get the easy interface." Not least among the new SOHO/SMB crossovers is the Yellow Machine from Anthology Solutions (www.anthologysolutions.com). We've been awaiting this unit for a long time, and between its announcement and now Buffalo Technology managed to slip into the space with its TeraStation, a four-drive NAS enclosure with a strong preference for RAID 5 configuration. However, the Yellow Machine differs from the TeraStation in a few important ways.
To Buffalo's credit, the TeraStation works on a Gigabit Ethernet port while the Yellow Machine is still 10/100. However, Anthology provides for a RAID 0+1 mode, a NAT- and SPI-based firewall and proxy server, and an 8-port LAN switch. Both boxes provide for FTP functionality, but Anthology also allows for the monitoring and recording of email traffic, which should be a serious perk to workgroup managers. And for all its features, the Yellow Machine is administered through a very intuitive browser interface. A stripped down version of the Yellow Machine is on sale at Fry's but otherwise Anthology sells 100% through the channel, banking on the fact that resellers can persuade buyers with the Machine's network function consolidation and impressive utility.
"Some resellers look at our unit and instantly get it," says Anthology's Stephen Dix, vice president of sales. "They understand what it is, how it fits into the world, and they have customers where all that's needed is just a knock on the door. Those resellers are moving lots of units. It's a quick and easy sale, and it's good margin. You don't see us at CompUSA or CDW at a couple dollars above cost. Unless a VAR decides to heavily discount it for some reason, he can be making in the 20% to 25% range, which is somewhat unusual these days." There are also a couple of other foundational technology changes afoot in storage that will help your sales in the long run. The first of these isn't something you'll probably sell actively, but it may come in handy to know about during the transition period: error correction code (ECC). "As hard drives get bigger, it gets harder for the ECC, because the error correction code stays the same size," says Seagate's Clark. "We're trying to squeeze in every bit possible for data, right? All the hard drive vendors are looking at moving from 512B to 1KB. That allows us to expand the number of bits used for ECC so that we can continue to provide reliable drives to the industry. You're not seeing 1K sectors today, but you should see everybody move to it next year." The second potential change is Storage-over-IP, or SoIP, which involves the use of Internet Protocol (IP) to help construct storage area networks (SANs). SANs are predominantly enterprise storage structures designed to link RAID controllers, tape libraries, and other storage devices to servers and then link those servers. Fibre Channel has been the usual medium of SANs, but Fibre is expensive and there have been compatibility issues among network switches and other devices. From 2003 to present, iSCSI has been an increasingly common way to run the SCSI command set over Ethernet, thus only requiring common Ethernet switches to bind the topology together. But iSCSI remains a complex, costly solution, and platform-selling start-up Zetera (pronounced like et cetera) thinks it has a better answer. "Decades ago, everybody decided that direct-attach storage was way too hard to manage, and we needed to centralize it," says Ryan Malone, director of channel marketing at Zetera. "From that line of thought came NAS, iSCSI, and Fibre Channel over the last few years. And all of those things have made really good efforts at trying to accomplish those goals of centralization and utilization. But they've only gone so far. Really, they've used IP as an extension cord for direct-attach disk commands. iSCSI is just an extension cord for a SCSI box. Same with Fibre Channel. NAS is just a remote file server that happens to live in a different part of the building or network. Zetera is the first and only commercially available realization of the storage-over-IP vision, which is, in a pure sense, about connecting pools of disks to a network without any of the other stuff between that makes it happen, like RAID controllers and dedicated switches and host bus adapters."
The company's "Z-SAN" technology maps IP addresses directly to the blocks on a disk drive. This allows devices to communicate in the same way that the Internet works. You don't need to know where a Web server is, only what the IP address is to get to that Web server. Z-SANs operate much in the same fashion. All of the storage elements are given IP addresses, and then basic IP maps group those elements together to form either very simple volumes or RAID structures. However, volume sizes can be quite large—all the way up to 128 petabytes or so per volume. And this is accomplished with off-the-shelf networking gear and none of the bandwidth constraint points caused by RAID controllers, NAS heads, host bus adapters, and other common bottlenecks. Data moves straight from the disk volume through the Zetera-based enclosure/adapter to the LAN switch and into the system. Additional servers, RAID controllers, HBAs, and such are eliminated. Research firm IDC has stated that a storage technology should ideally deliver on four criteria: affordability, scalability, performance, and reliability. Most solutions make compromises among these four points. Fibre Channel has pushed hard to be known as fast and scalable but at the expense of high cost. iSCSI has taken the middle of the road in wanting to be a less expensive version of Fibre Channel but is often constrained by bandwidth limitations in the IP fabric, meaning the LAN architecture, as well as some of the overhead involved in TCP/IP. NAS steers toward much lower price points but frequently does so, particularly at the low end, by sacrificing scalability and performance. Scalability and performance are where Zetera shines brightest. Because each disk volume has its own IP address and connects to the LAN fabric directly, each volume communicates at the connection's line rate. With striping employed, each disk that gets added to the array makes the array perform that much faster. "We win on all four of IDC's criteria simultaneously," says Jeff Greenberg, senior director of product marketing for Zetera. "Because we dispense with all those extra network components, we will always be the lowest cost network storage architecture today. From a performance standpoint, we've eliminated the bottlenecks associated with a NAS head or a Fibre 4Gb switch. If you want to go faster than 4Gb, you're hosed. Because we create an IP connection between the disk drive and the client through a switch, if I want to get bigger/faster/stronger, I just add more spindles to the array and I use a switch to aggregate performance. If I want 30 Mbps performance, I have one drive. If I want to have 300 MBps, I have 10 drives. If I want 3GBps, I have 100 drives." Zetera supports conventional RAID 0, 1, 5, and 6 (double parity stripe). However, Z-SAN protocol also provides for the ability to split disks into virtualized IP partitions that can combine stripes and mirrors on the same physical drive—sort of a distant and more advanced relative of Intel's Matrix RAID. This "Z-RAID" provides equivalent performance versus RAID 5, twice the performance of RAID 10, and "statistically superior" resistance to data loss in large arrays. To be clear, Zetera does not sell hard products. Rather, it's more like Dolby in that it devised a platform that can be licensed. The first company to convert this platform into a SKU is Netgear with its SC101 Storage Central. The little toaster-shaped device houses two drives and can be configured as a RAID 1 or a single spanned volume reaching up to 128PB. It's important to remember that there are no physical boundaries with a Z-SAN. The enclosure's two-drive form factor is strictly a point of convenience and consumer marketing. Currently, Zetera has two other vendors with striping-capable Z-SAN products in the wings. One of these is distributor Bell Micro. "We will be integrating and reselling 4-, 12-, and 16-drive solutions with as much SATA capacity as needed," says Bell Micro vice president Joe Cousins. "The four-bay box is an external stand-alone that has superior performance levels for very little cost. A 1TB box will sell for as little as $1,000, plus it's very easy to install and manage. You get lots of performance and almost unlimited capacity with no expensive controllers required. We are the only distributor in the channel for this implementation." SMB-oriented Z-SANs will have several competitive advantages, including how file shares get handled. With a NAS, you can share files, but SANs are more problematic. There is commonly no synchronization control to prohibit two computers accessing the same file at the same time and corrupting it. Zetera offers a built-in multi-initiator file system which manages that control so files and volumes can safely be shared among multiple users. Normally, this represents a very expensive add-on for a SAN, which is why it's not often done. "Down in the SMB space, they don't understand this NAS vs. SAN distinction," says Zetera's Greenberg. "They just expect everything to be shared. So we built this multi-initiator file system so it can be shared the way they think it should be. But also, a SAN is a block-based device which can be used by something like an exchange server or a database server directly. You can't do that with a NAS. But with our technology, you can have one little box that is an Exchange or Oracle server and it can be a general purpose shared file repository for the people in the organization." ...more |
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