First-Class NAS

The rapid acceleration of storage needs and the desire for simple, manageable devices has thrust network-attached storage into the spotlight as a top-flight option.

August 19, 2003

18 Min Read
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NAS devices comprise basic server hardware and storage components. Essentially, they're servers with a ton of storage. The secret sauce that turns these devices into turnkey appliances is specialized NAS operating systems. Some machines run the Microsoft SAK (Server Appliance Kit), a stripped-down version of Windows 2000 Server for use on NAS devices. With SAK, the NAS device can natively run some Windows software, such as backup agents. SAK also saves you the cost of a full-blown Windows server license for your NAS box. Many other NAS machines run a Unix variant, such as Linux or FreeBSD. Other companies have hand-coded their own tight kernels, which may seem impressive but often offer few advantages.

NAS Device Performance

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NAS Lineup

To test midrange NAS devices, we invited 20 vendors to send us systems priced from $5,000 to $30,000. We asked for at least one copper Gigabit Ethernet port and recommended that vendors send 1 TB of storage with enough spindles to ensure maximum performance.

We received machines from Dell, Excel Meridian Data, First Intelligent Array (FIA), Hewlett-Packard Co. and Procom Technology. Advanced Media Services, Auspex Systems, BlueArc Corp., Delta Networks, EMC Corp., Gateway, Hitachi, IBM, JES Hardware Solutions, Network Appliance, Network Storage Solutions, RaidZone, Rare Systems, Snap Appliance and Sun Microsystems received invitations but declined to take part in our tests.

The participants all complied with the 1-TB minimum and included two or more copper Ethernet NICs. Prices ranged from $14,745 (for Excel Meridian's NetStor MVD) to $29,995 (Procom's NetForce 1800). Beyond the basics, however, we got quite a mix of hardware and physical configurations: internal disks, external disks, SCSI connect, Fibre Channel connect, and a multitude of Ethernet connections of varying speed and type.Our tests gauged the performance of CIFS and NFS, using SourceForge's Iometer (see performance test results in chart on this page). In choosing our winner, we also considered ease of setup and administration, as well as fault-tolerance and scalability features, warranty and price.

To select the best NAS system for your enterprise, consider current and future storage demands, expected traffic and backup requirements. Your NAS should be expandable to suit your needs two years from now. Anticipating the traffic your NAS device will handle down the road will help you decide whether to get a second NIC on your unit and whether to use Gigabit Ethernet connections. And because you have several backup options, also think about your preferred backup method before you choose a device. Many NAS devices take a snapshot--a point-in-time backup of the current drive. However, snapshots take up space, especially if you use them extensively. You can make full backups with protocols such as NDMP (Network Data Management Protocol) or via a local tape, but your backup window and medium must be able to handle the additional stress the new NAS device may introduce.

On the hardware side, consider the importance of the data you are putting on the NAS. How fast does it need to be accessed, and how quickly does it need to be restored in the event of a failure? The faster you need that data, the more important multiple power supplies and redundant fans become. The drive choice is paramount: Conventional parallel ATA/IDE drives are slower and generally have less MTBF (mean time between failure) than their SCSI and Fibre Channel counterparts.

The combination of strong performance, a good warranty, flexible configuration and a decent interface make the Dell PowerVault 775N our Editor's Choice.The PowerVault 775N is one of two units we tested that use Windows SAK as its base operating system. We were a little skeptical of this approach. After all, why buy a NAS if you're just going to load Windows? However, between SAK and the vendor's customization, both the PowerVault and HP's StorageWorks NAS B3000 were good contenders, with some inherent advantages over their Unix variant-based counterparts. The fact that Dell's unit costs about $10,000 less than HP's gave it a big edge--and thus, our Editor's Choice award.

The PowerVault 775N is a relabeled PowerEdge 2650 server connected via a PERC3 RAID card to a PowerVault 220s Ultra 320 SCSI JBOD and loaded with the Windows SAK. Although that may not sound exciting, the combination makes an impressive NAS device. This machine is loaded with two 2.4-GHz Intel Xeon processors and 1 GB of RAM. The PowerVault has all the familiar server features of a Dell PowerEdge server, including DRAC (Dell Remote Access Card) and front-panel diagnostics with the LED and ActiveBezel that we like. Two onboard copper Gigabit Ethernet ports on their own PCI-X bus provide network connectivity. For expansion, the PowerVault 775N has two 100-MHz PCI-X slots and one 133-MHz PCI-X slot on different buses to provide ample bandwidth. The PowerVault supports up to 16.7 TB of storage for your users and applications.With all that hardware goodness and bus bandwidth, you might think the unit ran away with testing. Almost, but not quite. In CIFS testing, the 775N did well on the linear write tests, but fell down on the linear read tests. However, it did win the NWC CIFS Generalized Custom Test and only lost the CIFS IOps test to the HP unit by a thin margin. On the NFS side, the PowerVault performed predictably poorly, as Windows-based systems often falter on NFS testing.

NAS Device Features

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Managing the PowerVault 775N is a breeze. You can use the prefabricated menus to configure the system, or control the machine directly via terminal services--very nice. If you can administer a standard Windows 2000 Server, you'll have no trouble managing the PowerVault 775N--it's visually indistinguishable from a Windows 2000 Server installation. If you prefer a NAS appliance's look and feel, the configuration menus available from the Web browser interface are easy to use. You also can manage multiple appliances from one interface; the 775N will discover other Dell NAS devices via an agent on all Dell NAS machines. Administrators in Dell shops will especially appreciate being able to manage the 775N with Dell's OpenManage server management software.

Dell offers standard snapshots called ActiveArchives, NDMP and any standard Windows Server 2000 agent for backup software, which is a huge advantage for Windows-powered NAS devices. The 775N also offers seamless integration with Windows directory and authentication services, including ADS, another advantage. Of course, you can use local authentication to secure the machine. Dell offers a number of software options, including virus scanning, for an additional fee.

The Dell PowerVault 775N comes with a three-year, on-site, next business day parts and labor warranty.

Dell PowerVault 775N, Dell, (512) 338-4400, (800) 999-3355.

We were impressed with the NetStor MVD. The least expensive unit of the bunch, this NAS device has fine configuration and management features. However, the system's biggest drawback is its lack of integration with ADS, and its excellent performance numbers came with a minor caveat.The MVD software is based on Red Hat Linux and is produced by a third party, Mountain View Data. The device we received came with 1 TB of external Ultra320 SCSI storage redundantly connected to the head unit. It can be expanded to 16 TB. The head unit comes with two copper Gigabit Ethernet NICs and can hold up to four more NICs. The heart of the machine is a 2.4-GHz Intel Xeon processor with 1 GB of RAM. The head unit is actually a Supermicro machine--a Supermicro case with a Supermicro motherboard. It has dual power inputs with dual hot-swappable redundant power supplies. The RAID controller is integrated into the external chassis.

The NetStor MVD turned in some good test results--so good we had to look twice. Turns out the vendor had enabled write caching on the head unit, and the external RAID array comes with write caching turned on by default. Turning on write caching will do wonders for performance, but it's a dangerous practice without using a UPS unit. This is not a big deal; however, the decision should be left to the customer based on performance and data-protection needs. That said, even when we turned off write caching, the NetStor MVD performed very well, turning in winning numbers on the CIFS linear read and the NFS linear write tests. The unit was snappy and deftly handled everything we threw at it.

The NetStor MVD's easy-to-use management interface is accessible from a Web browser at Port 20000 (the others use Port 80). We found that little twist an interesting and wise security move. However, the interface doesn't allow integration with ADS--just Windows Server 2000-style permissions administered from the MVD administration interface. The base software allows for up to 32 concurrent snapshots and can be upgraded to 64 snapshots for a fee. It supports an external tape array directly attached or NDMP backup over the network.

The NetStor MVD isn't the most capable NAS we tested, primarily because of its ADS integration limitations. It also has a short, one-year cross-ship parts warranty and security administration limitations. Nevertheless, at $14,745, it's worth a second look.

Excel Meridian Data NetStor MVD, Excel Meridian Data, (800) 995-1014.

The mediocre performance and high price of HP's StorageWorks NAS B3000 underwhelmed us. The B3000 uses common HP server hardware, customized with a slick front panel. The main unit is connected to HP's MSA1000 Storage Array by a single 2-Gbps Fibre Channel connection. That array comes with a small FC switch embedded in the backplane and is a full external RAID array with Ultra320 SCSI drives. You can scale the B3000 to an impressive 48 TB--the largest among the devices we tested--using the MSA1000 Storage Arrays.The head unit is loaded with a 2.8-GHz Intel Xeon processor and 2 GB of RAM. Network connectivity is provided by two copper Gigabit Ethernet interfaces on their own PCI-X bus integrated onto the motherboard. These Gigabit Ethernet interfaces can be teamed for load balancing and failover. Software for that function comes preloaded on the B3000. There are two 100-MHz PCI-X slots and a 133-MHz PCI-X slot. This unit also comes with HP's well-designed iLO (integrated Lights Out) management solution, an out-of-band remote access card that allows access to the server even when the server operating system isn't loading.

In testing, the StorageWorks NAS B3000 exhibited only average performance. It won only the CIFS IOps test and managed to place in a couple of others, but overall performance was unimpressive. As with Dell's Windows-powered NAS, the B3000 had difficulty with the NFS tests.

The interface is that of an HP-customized Windows SAK box. It's easy to use, clean and offers the option of simply starting a terminal services session to access the desktop directly. HP uses CDP Persistent Storage Manager to provide up to 256 snapshots with flexible scheduling. HP gives you a taste of its HP NAS Data Copy with a 30-day trial for remote mirroring/

replication. Of course, the B3000 integrates with ADS as seamlessly as any other Windows server for authentication and security.

The B3000 comes with a three-year, next-day, on-site warranty.HP StorageWorks NAS B3000, Hewlett-Packard Corp. (650) 857-5518, (800) 888-9909.

Barely expandable and underperforming, the FIA POPnetserver 8000 can't even lay claim to being the least-expensive NAS we tested. For those reasons, we can't recommend this unit to companies with minimal storage needs and small budgets.

The POPnetserver 8000 is the only ATA/IDE unit we received. It has no support for external storage, and came in a RAID 5 format: eight 250-GB Maxtor drives in hot-swappable carriers in the front of the 2U machine. Of those 2 TB, about 1.5 are usable, with 500 GB reserved for RAID 5's redundancy. We got a chance to use the hot-swap carriers, as disk one in the system developed a sector error soon after we powered up the machine. FIA's tech support send us a new drive overnight. We hot-swapped the drive and the array immediately began to rebuild.

Our test unit came with two 2.4-GHz Intel Xeon processors, 1 GB of memory and a whopping four network ports: two 10/100 and two 10/100/1000 copper Gigabit Ethernet ports. Unfortunately, they are not very clearly labeled and not laid out in an expected pattern. Power is supplied by separate sources in the form of two hot-swappable power supplies that can be accessed from the back of the machine. The unit also features three PCI 64-bit/66-MHz buses for the two IDE RAID cards and all four NICs. This should provide plenty of bandwidth for the NAS.

Unfortunately, the POPnetserver 8000 managed to lose out on just about every test we ran. It never captured a top spot, though it occasionally placed second. We attribute most of its performance issues to the IDE/ATA disks, rather than to the base NAS OS, the FreeBSD-based POPnet OS.

We liked the POPnetserver 8000's management interface. It was one of the easiest to understand and configure. The POPnetserver 8000 supports snapshots, server-to-server replication and graceful shutdown in the event of a UPS emergency with American Power Conversion UPS units. Regrettably, the POPnetserver 8000 does not support the NDMP backup protocol.The POPnetserver 8000 comes with a three-year parts and labor warranty on a cross-shipment or carry-in basis. Although we find the price attractive, the lack of expandability and poor performance make us pass on this unit.

POPnetserver 8000, First Intelligent Array, (949) 940-6565, (888) 353-0337. The Procom NetForce 1800 was one of two units configured as a single device with internal disks, rather than a system with separate head and storage components. The NetForce 1800 is a solid performer on the NFS side of things, but all in all it's an average machine with a hefty price.

The Procom NetForce 1800 is a 2U unit with a 3.06-GHz Intel Xeon processor and 4 GB of RAM. Network connectivity is provided by two 10/100/1000 copper Gigabit Ethernet ports; the device we received also had a fiber gigabit NIC. Dual-input power leads to two hot-swappable power supplies, accessible from the rear of the machine. The unit supports a local tape drive or external storage, to bring its total possible capacity up to 6 TB. On the front of the machine, a neat little LCD displays CPU utilization and lets you configure the network without having to console into the unit or let it use DHCP. The NetForce 1800 has plenty of internal bandwidth, thanks to an Intel motherboard and 64-bit/66-MHz slots to sustain high transfer rates. You can also bond like NIC ports together for load-balancing/failover configurations.

In our tests, the NetForce 1800 did particularly well at the NFS tests, winning all the linear read, IOps and NWC Custom tests. On the CIFS side, the NetForce 1800 performed well, frequently finishing second or third. We found the CPU utilization on the machine's front handy for indicating when the CPU had maxed out. The Excel Meridian unit and the FIA unit did not have any way--short of going to a Unix console with special access--to see what their CPUs were doing, and the Windows-powered HP and Dell units simply used Perfmon. CPU monitoring on NAS devices is generally lacking, but the Procom unit shined there.

The NetForce 1800 stumbled on its clunkily designed, Java-based management interface. Everything is nested in expandable menus and the whole thing is graceless, though it is usable and we had no problem playing with the device's features. The NetForce 1800 also comes with a journaling file system that recovers much more quickly than machines that use Microsoft's SAK in the face of a power-loss event.The unit's software features were complete. The NetForce 1800 supports standard snapshot features (which Procom calls checkpoints), NDMP backup, user quotas, Windows ADS support and support for older Windows PDCs (Primary Domain Controllers).

The base warranty that comes with the Procom NetForce 1800 is three years depot with one year of cross-shipment. Software phone support is available only for a disappointing 90 days. Longer warranty periods with faster service and longer software phone support can be purchased. You'll pay dearly for this unit, though.

Although the NetForce 1800 stayed within our price range, at $29,995, that's more than double the least expensive unit in the bunch.

Procom NetForce 1800, Procom Technologies, (949) 852-1000, (800) 800-8600.

Steven J. Schuchart Jr. covers storage and servers for Network Computing. Previously, he worked as a network architect for a general retail firm, a PC and electronics technician, a computer retail store manager and a freelance disc jockey. Write to him at [email protected].Post a comment or question on this story.Network-Attached Storage

So you don't need an all-out storage-area network, but your network has outgrown its capacity beyond simple, direct-attached storage. Network-attached storage devices fill the gap, providing reasonably priced storage with specialized operating systems that can manage data with a wide variety of protocols.

We tested five midpriced NAS devices for this review--Dell's PowerVault 775N, Excel Meridian Data's NetStor MVD, Procom NetForce 1800, Hewlett-Packard's StorageWorks NAS B3000 and First Intelligent Array's POPnetserver 8000--all of which range from about $15,000 to $30,000. They offer NFS (Network File System), Windows shares and HTTP shares, and usually can be configured in 15 minutes. Try that with your average SAN.

Our Editor's Choice, Dell's PowerVault 775N, is a well-customized unit that uses the Microsoft Windows Server Appliance Kit, has the best mix of features and performance, and is near the low end of the price range.

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We tested midrange NAS devices in our Green Bay, Wis., Real-World Labs withSourceForge's Iometer 2003.5.10. We used 10 2.4-GHz Pentium 4 client machines,with network connectivity courtesy of an Extreme Networks Summit7i switch and aCisco Catalyst 6500 with a copper Gigabit Ethernet card. Five machines werehooked to our north subnet and five to our south subnet. On each NAS, oneGigabit Ethernet NIC was connected to each segment. An 11th machine servedsolely as our Iometer console.

Our Iometer tests gauged CIFS (Common Internet File System) performance and NFS(Network File System) performance.On the CIFS side, we performed the following tests: 64-Kbps linear read test;64-Kbps linear write test; 1-MB linear read test; 1-MB linear write test; 2-MBlinear read test; 2-MB linear write test; CIFS IOps and NWC CIFS GeneralizedCustom Test.

For all linear read and write tests, the percent read/write distribution was setto 100 percent read for the read tests and 100 percent write for the writetests. Percent random/sequential distribution was set at 100 percent sequential.Our CIFS IOps test had a 512-byte transfer request size, and was also set to 100percent read and 100 percent sequential.

The NWC CIFS Generalized Custom Test had transfer request sizes of 512 byteswith 33 percent access distribution, 2 KB with 34 percent access distribution,and 64 Kbps with 33 percent access distribution. On the 512-byte segment, thepercent read/write distribution was set at 100 percent read and the percentrandom/sequential distribution at 100 percent sequential. The 2-KB segment had a67 percent read and 33 percent write distribution and the percentrandom/sequential was set at 100 percent random. On the 64-Kbps segment, we setthe percent read/write distribution to 100 percent read and the percent random/sequential distribution to 100 percent read.

On the NFS side, we performed these tests: 64-Kbps linear read test; 64-Kbpslinear write test; 1-MB linear read test; 1-MB linear write test; 2-MB linearread test; 2-MB linear write test; NFS IOps and NWC NFS Generalized Custom Test.We performed the NFS linear read and write tests with the same parameters asthose of the comparable CIFS tests (100 percent read or 100 percent write, and100 percent sequential). However, on the NFS IOPS test, we used a 4-KB transferrequest size, rather than the 512-byte size we used for the CIFS test.

Furthermore, our NWC NFS Generalized Custom Test featured transfer request sizesof 4 KB with 33 percent access distribution, 4 KB with 34 percent accessdistribution, and 64 KB with 33 percent access distribution. On the first 4-KBsegment, we set the percent read/write distribution to 100 percent read and thepercent random/ sequential distribution to 100 percent sequential. On the second4-KB segment, we set the percent read/write distribution to 67 percent read-33percent write, and the percent random/sequential to 100 percent random. On the64-KB segment, the percent read/write distribution was 100 percent read and thepercent random/sequential distribution was 100 percent read.


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