NAS for the rest of us: 4 storage solutions
We test and compare NAS devices designed to suit a specific set of medium-enterprise requirements.
Initially, we are looking for a "box" that plugs into a gigabit Ethernet network and can service all manner of clients including Mac, Linux, and Windows using their respective native file systems. Of course, your needs may extend further and you may need the NAS to exist with Novell Netware for example.
Before buying a NAS you must consider your requirements for the following:
- Network Transport Protocols
- Network File Protocols
- Network Client Types
- Server Emulation
- Network Security
It would be nice if the NAS chassis had enough space to simply install some extra drives, and this is also the least expensive upgrade option. Some of the units tested however have a limited number of drive bays -- generally because of their svelte form factor -- and have already reached their drive limit at our 1TB configuration.
You then have two options: replace the existing drive set with larger- capacity drives or purchase an additional NAS or storage array. The former, the least expensive option, is only available if you can take the NAS offline -- if you cannot afford to take the NAS down to perform the upgrade, or if it is already configured with the largest- capacity drives available, then you are up for the most expensive option of purchasing more hardware.
Adding more drives or simply replacing the old drives with larger-capacity drives varies in cost.
Some of the NAS units feature inexpensive PATA or SATA drives that are available in increasingly large capacities for relatively little expenditure, while other units have Ultra SCSI drives that are significantly more expensive and tend to lag the ATA drives in terms of capacity. For example, on the Seagate Web site we found PATA drives of 400GB capacity but the largest Ultra 320 SCSI drive was only 300GB.
Quite frankly, SCSI drives still have a higher mean time between failure (MTBF) than ATA drives if you look at the vendors' specifications.
Although this gap is closing as the MTBF of many of the vendors ATA drives continue to increase, we would still expect the SCSI drives to have a lower failure rate in a heavily-utilised NAS.
So if reliability is critical and you expect the NAS to take a pounding, then SCSI would be a safer bet. If, however, the load on your NAS is not too high or the thought of replacing a drive occasionally when they fail does not worry you then ATA drives would do nicely.
Can you afford the possibility of the NAS going down?
Probably not, so you should seriously consider redundancy, and this does not begin and end with redundant power supplies. Other redundant features can include LAN and Fibre Channel ports, disk controllers, and in some cases the entire NAS controller is duplicated.
Generally if the NAS does have duplicated ports or controllers these can be configured to load balance, further improving the unit's performance when it's in its peak of health.
EMC's NAS solution was nearly an "almost ran" in this review as it arrived at the Lab in two deliveries, several days apart, and then with parts missing or the wrong parts supplied. It also uncovered a problem with EMC's training of local technical support staff at LAN Systems -- quite simply it is inadequate and on several occasions we found it necessary to seek support at EMC's support centre in Toronto. While the calls were free and no more difficult than a local call, we feel that EMC has a duty to ensure local support staff are adequately trained.
Setting up the EMC solution is a bit of a jigsaw puzzle -- the dual-controller storage chassis, the AX100 controllers each have a Fibre Channel connector while the NetWin 110 server which provides NAS connectivity to the network only has a single fibre channel connector. To connect both AX100 controllers to the NetWin, a Fibre Channel switch is required and an EMC 3250 VL2E was supplied to do the job. Sadly, we only received two cables and did not receive a third in time for testing so were only able to connect the server to a single AX100 controller. We were informed by the local support staff that this should have no impact on performance.
EMC has designed the AX100 to only fire up if it is connected to a UPS via its serial connector, a sensible safeguard. As a consequence, the unit shipped with an APC SmartUPS 750, which only has a single conditioned AC-out connector and so can only connect to one of the two controllers.
The AX100 required 2RU, the NetWin 1RU, SmartUPS, another 1RU, and finally the 3250 VL2E another 1 RU for a total of 5RU. Admittedly, you may already have your own Fibre Channel switch but, even so, the EMC requires a lot of a rack space.
On the upside, the AX100 packs a lot of drives into a 2RU chassis, up to 12 SATA drives. Our test unit was configured with five 250GB SATA drives, one of which was reserved as a hot spare, so seven drive bays remain free. With all bays occupied, the EMC machine claims up to 3TB of raw disk space.
The drive cradles themselves are very minimalist and, we must admit, feel flimsy and clumsy particularly when compared to the Apple.
The NetWin is a relatively standard 1RU server with no advanced redundancy features and just a single power supply. The Fibre Channel connectivity is provided by an Emulex PCI-X card; it's a pity EMC did not see fit to provide a dual-channel card for those that don't need a Fibre Channel switch.
The AX100 is a far more substantial unit than the NetWin, and has taken redundancy quite seriously with two of everything: two controllers, two CPUs, two sets of I/O, and two power supplies.
Installation and configuration was more painful than it should have been, if all the components had been supplied from the beginning then the setup would have been a lot smoother.
However, we did experience a problem with the server and were unable to run it's Web-based management software Navisphere. We tried several tricks and none worked so finally the server's operating system was reinstalled via the provided Restore DVD; this fixed the problem.
A software applet is used to initialise the AX100 and from that point on all management is carried out via Navisphere, although the management of the AX100 is a little clumsy because the Web user interface (UI) Navisphere launches a second Web UI in the initial browser and at times you have to scroll about because you cannot view the full AX100 configuration window. It would have made more sense to spawn a new browser window.
Navigation around the UI is straightforward and we found configuring drives and volumes along with the relevant shares to be a simple matter. Bundled software is quite useful with a volume "snapshot" utility and a second, PowerPath, which is certainly worth more attention. PowerPath is in essence an I/O path management tool that intelligently routes I/O to provide multiple paths, load balancing, and path failover should a router die for example. Admittedly, this is overkill for our simple scenario but as your storage network grows PowerPath would become a very useful tool.
The EMC was consistently slower than the other two units, at times by a large margin. Admittedly, the Sun had an advantage over all the other units in terms of onboard memory but the Snap and EMC were similar in configuration and the Snap was significantly faster. In terms of cost per GB the EMC was also quite expensive at AU$32.21/GB, only the Sun had a higher cost per GB.
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The 4500 is the smallest of the devices tested at just 1RU and, not surprisingly, its internal mass storage capability is less than the larger units. The 4500 has four 3.5in drive bays that accommodate PATA drives -- the least number of storage bays of the units tested. While the 4500 was provided with four 250GB drives in it's RAID 5 configuration, we only see around 750GB of storage. If you want more, the 4500 is available with 400GB drives for a total capacity of 1.2TB. Up to two external Snap Disk 10 expansion arrays can be controlled by the 4500, each with four storage bays for a maximum capacity of 3.6TB, again the lowest expansion potential of the units tested.
The hot swap drive cradles are quite impressive, solid metal fabrication that guides the drive into the bay to ensure accurate mating of the connectors with a minimum of fuss. The remainder of the 4500 chassis is also reasonably robust although the cooling, while apparently adequate, is the least impressive of the units tested. There is a small fan to cool the two PCI-X slots, one of which is occupied by a SCSI card to enable a tape backup to be directly connected to the external port it provides.
There are no redundant power supplies, just a single 250W unit with dual cooling fans. Connection to the LAN is via a pair of gigabit Ethernet ports. The 4500 is easy to install and remote configuration and management is also exceptionally easy thanks to the user-friendly Web-based interface.
Admittedly, the unit we tested arrived fully configured with RAID 5, but the RAID Wizard in the Web interface is straightforward making it a painless exercise if you have to configure it yourself.
Interoperability is very good with support for Windows, Unix, and Apple file systems and many of the most common clients are also supported. Network connectivity is via a pair of gigabit Ethernet ports and the 4500 has iSCSI target support.
There is a useful collection of bundled software supplied although only two are full copies; Bakbone Netvault Workgroup Edition and Symantec Powerquest Datakeeper (desktop backup); the remaining software packages are supplied as 30-day or 45-day trial editions.
Given its low price, the performance of the 4500 was also a surprise. The 4500 was at times quite close to the Sun in terms of throughput per second, and during the simultaneous Read/Write test it was slightly faster than the Sun. And because of the 4500's low cost per GB, it was by a large margin the lowest of all the units tested at just AU$9.73/GB.
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Of the four units supplied only the Snap Server and Sun StorEdge are "single box" solutions. The Sun machine is substantially larger than the Snap with a 2RU case, and although it is twice the size of the Snap we were surprised that the Sun only manages another two drive bays for a total of six bays. The unit supplied to the Lab was configured with six 140GB Ultra SCSI 320 drives, five of which were in a RAID 5 configuration amounting to 560GB, and the sixth retained as a hot spare. Sun currently does not have higher capacity drives and so this is the internal expansion limit for the 5210.
External storage is another matter, up to three expansion units can be attached to the 5210; each with 12 drives for a total of 42 drives and around 6TB of raw unconfigured disk space or 4TB in a similar configuration to the 5210.
The hot swap drive cradles are plastic and, while not flimsy, are not as impressive as the Snap's. It also is not as smooth in operation as the Snap, it generally involves some "jiggling" to line up correctly upon insertion.
There are a pair of hot swap redundant 500W power supplies and the PCI-X Ultra SCSI 320 RAID controller includes battery backup for its 128MB of cache. With a total of six PCI-X slots, only one of which is used, there is plenty of expansion potential although we should note that three of the slots are only half height.
Like the Snap, the 5210 arrived with a preconfigured RAID 5 drive array but the Sun also has a hot spare. And, like the Snap the 5210, it has a simple Java Web interface for configuration and administration.
The Interface appears bland when compared to the Snap but we found it looked cleaner and its tree structure was very simple to navigate.
Interoperability is very good and in general on par with the Snap although the Snap offers Windows server emulation while the Sun does not, and Sun's iSCSI support is not due until June this year.
The Sun has a Journaling file system which writes the Journals directly to disk, this precludes the loss of data that would occur if the NVRAM head unit of other vendors NAS should fail.
Also standard on the Sun is a user configurable File Checkpoint feature which only duplicates disk blocks when they are modified and also only duplicates the modified sections of files thus reducing disk space required and the time taken to create the checkpoint.
The Sun is not an inexpensive NAS, its cost per GB is the highest of all the units tested but thankfully its performance does live up to the high price tag and, let's face it, Ultra SCSI 320 drives are significantly more expensive than the PATA and SATA drives featured in two of the other NAS. In almost every test the Sun had significantly higher throughput than the other NAS, the only exception was in the simultaneous read/write test where the SnapServer was slightly faster. However, we have no doubt that if the test were repeated with a much higher load and more clients the Sun would pull ahead of the SnapServer.
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Unfortunately Apple's product arrived too late to run the complete series of tests.
While the Apple solution consumes more rack space than any of the other solutions tested (4RU) it does feature more drive bays than any of the other solutions -- 14 in total, compared to the EMC's 12 bays. And Apple really packs in high-capacity drives.
The test unit was delivered with 5.6TB, its maximum, on board which far exceeds any of the other units tested, in terms of internal capacity. In most cases the Apple exceeds the other units' total storage capacity with external arrays. Multiple Xserve RAID arrays can be configured to support a single partition up to 16TB is size. The XServe G5 is a 1RU and the Xserve RAID 3RU and there is no doubt that in terms of construction the Apple products are the Rolls Royce of the NAS solutions tested.
The XServe G5 is gorgeous once you take the lid off, and the attention to detail in the internal layout is first class. The XServe RAID box is built like the proverbial tank, and it is a two person exercise to move it about.
The RAID unit has two sets of "Drive Modules", ie, the 14 PATA drives are divided equally into two sets of seven, each with its own controller. It's a pity but the drive controllers do not seem to load share or provide redundancy should one fail.
The XServe RAID is more serious than the Server with regards to redundancy, as mentioned there are two controllers each with their own gigabit Ethernet, Fibre Channel, and power supplies. The drive cradles are the most impressive we have seen with a rugged construction and silky-smooth insertion and removal. There is also a drive lock to prevent unauthorised removal of the drives, a wise addition.
Specifications
| Product | XServe G5 Server and XServe RAID Array | EMC NetWin 110 and Clariion AX100 | Snap Server 4500 1TB | Sun StorEdge 5210 |
| Company | Apple | EMC | Adaptec | Sun |
| Phone | 133 622 | 02 9922 7888 | (02) 8875 7874 | 1 800 628 193 |
| Web site | www.apple.com.au | www.australia.emc.com | www.adaptec.com | www.sun.com |
| RRP inc GST as tested | AU$30,224 | AU$32,207 | AU$7,299 | AU$21,756 |
| RRP inc GST in 1TB configuration | Xserve G5 server 1.2TB of storage -- AU$10,274 1TB useable in the Xserve RAID connected to the Xserve -- AU$18,224 | AU$32,207 | AU$7,299 | AU$40,361 inc GST |
| Form factor | Xserve G5 Server 1U Xserve RAID Array 3U | NetWin 110 (Server) 1U Clariion AX100 (Storage Array) 2U APC SmartUPS 750 (UPS) 1U EMC 3250 VL2E Fibre Channel switch 1U | 1U | 2U |
| Number of drive bays occupied/free | 14 / 0 | 3/9 or 4/8 | 4 / 0 | 6 / 0 |
| Hot-swap drive bays | Yes | No | Yes | Yes |
| Drive Type and model | Hitachi Deskstar 400GB ATA | Maxtor Maxline Plus II 250GB SATA/150 | Maxtor Maxline Plus II 250GB ATA/133 | Hitachi DK32EJ-14NC 146GB Ultra SCSI 320 |
| Drive RPM | 7200 | 7200 | 7200 | 10000 |
| Disk connectivity | ATA | SATA | PATA | Ul,tra SCSI 320 PCI-X controller card |
| Tested array size / maximum supported by NAS/storage array (internal) | 5.6TB (total of 14x400GB). | 1TB useable up to 3TB (raw) | 4500 supplied as RAID 5, 4 x 250GB = 750GB capacity / 4 x 400GB = 1.2tb capacity | 560GB (with 140GB hot spare) / 560GB |
| External storage array support | Multiple Xserve RAID arrays can be configured as a single, dynamic SAN volume using Xsan software for Mac OS X. Currently the largest single volume supported with Xsan is 16TB. | Directly attached 1xAX100 per NetWin 110 server for a total of 3TB (raw). NetWin110 attached to switch then multiple AX100 per NetWin NAS Gateway. | Up to two "Snap Disk 10" storage arrays can be attached each 1U with 4 drive bays and 1.2TB total capacity | Up to three Expansion units can be attached each with 12 drives for a total of 42 drives and 6.1 TB unconfigured. |
| RAID types supported | 0, 1, 3, 5, 0+1 | 5 | 0, 1, 5 (with global hot spare support) | Hardware RAID 5 only |
| Ethernet (number of ports and speed) | Xserve G5 Server: Two gigabit ports Xserve RAID Array: two 10/100TX for management (file sharing or general data access is done via the server gigabit ports) | NetWin 110 (Server) 1 x 1Gb & 1 x 100TX (maintenance port) Clariion AX100 (Storage Array) 2 x 1Gb & 2 x 100TX (maintenance ports) | Two 10/100/1000 ports | Two 10/100/1000 ports (Copper or optical) |
| CPU/s | 2 X 2.3GHz G5 (64-bit) | NetWin 110 (Server) 2.4GHz P4 Clariion AX100 (Storage Array) P4 | One 2.4GHz P4 | One 3.06GHz Xeon CPU - provision for a second CPU |
| Memory (standard/maximum) | 1GB/16GB (tested with 3GB) | NetWin 110 (Server) 1GB / 1GB Clariion AX100 (Storage Array) 512MB for single controller, 1GB for dual controller | 512MB / 3GB of DDR ECC | 4GB/4GB (6 slots with 2 free-future expansion TBA) |
| NAS OS | MAC OS X Server v10.3 | MS Storage Server 2003 (NetWin 110) | GuardianOS V 3.1.079 | StorEdge NAS OS, OS resides on flash disk |
| Redundant power supply | Xserve G5 Server: Single Xserve RAID Array: Dual redundant | NetWin 110 (Server) NO Clariion AX100 (Storage Array) Yes 2 | No, Single only | Dual redundant 500W power supplies |
| Network transport protocols supported | TCP/IP, AppleTalk | CIFS, NFS, TCP/IP | TCP/IP, UDP/IP, AppleTalk | TCP/IP, |
| Network file protocols supported | Macintosh (AFP, AppleTalk PAP), Windows (SMB/CIFS), UNIX and Linux (NFS, LPR/LPD), Internet (FTP, WebDAV) | NFS | MS CIFS/SMB, Unix NFS v2/3, Apple AFP 2.0, Web HTTP 1.1, FTP | MS CIFS/SMB, NetBIOS, NFS v2 & 3, FTP |
| Network block protocols supported | Full Fibre Channel block level support is included for SAN and DAS implementations. | AX100i - iSCSI support | iSCSI (target support) | ISCSI (available June 2005) |
| Network client types supported | Open Directory 2 (OpenLDAP, Kerberos, SASL). Windows, Red Hat Linux, MAC OS. | Mac, Unix (Solaris), Linux, Windows, Netware | Windows 95 through XP, Mac OS 8.x 9.x 10.x, Solaris 7 - 9, HP-UX 11, AIX 4.3.3, Red Hat 7.2 8.0 9.0 | Windows 95 through XP, Solaris 7 - 10, HP-UX, AIX , Red Hat |
| Server emulation | Win NT, OS X, NFS, FTP. | Active Directory Integrational, NTFS, Disk Quotas, VSS (Volume Shadow Copy Services), Exchange 2003 support | Windows NT 2000 2003, AppleShare 6.0, NFS v2/3, FTP | NFS v2/3, FTP |
| External Interfaces (eg iSCSI, Fibre Channel, etc) | Xserve G5 Server - dual port FC HBA Xserve RAID Array - two 2GB FC controllers | NetWin 110 (Server) 1 x Fibre Channel Clariion AX100 (Storage Array) 4 x Fibre Channel (2 per controller) | Ultra2 SCSI (backup interface) | 3 x Ultra SCSI 320, 3 USB |
| UPS support | Yes | NetWin 110 (Server) - No Clariion AX100 (Storage Array) - Yes | Yes | Yes |
The test environment was a small network was setup in the lab comprising the following:
- NAS under test
- 3com SuperStack3 10/100/1000 Switch
- Client - Dell PowerEdge 6600 Quad Xeon server with 3GB of memory, gigabit LAN connectivity, SCSI RAID 5 array and Windows Server 2003.
Windows File Copy Tests
A series of files were copied to and from each NAS from our Windows Server 2003 client to look at common file transfer speeds using a variety of file sizes as shown below:
- Test 1: A single ZIP file of 1,967,101,917 bytes (copied to NAS)
- Test 2: A collection of 3401 files in 342 folders totalling 2,246,716,585 bytes (copied to and read from NAS)
- Test 3: A collection of 13,222 files in 1237 folders totalling 5,995,670,198 bytes (Copied to NAS)
This company needs additional storage to cope with the rapid expansion of its e-mail and other storage needs.
Approximate budget: AU$40,000.
Requires: 1TB of total storage, either in one or two units, with gigabit Ethernet network connectivity and fibre channel for future SAN connectivity.
Concerns: In addition to the performance of the storage unit(s), the ability to manage the unit(s) easily and to integrate with current systems such as directory servers will be very highly regarded.
For maximum uptime, redundancy of disks, power supplies, and network connections will also be a consideration.
Best solution: SnapServer 4500
It's a bit of a tussle between the least expensive NAS tested and the most expensive in terms of cost per GB.
At AU$38.85/GB the Sun StorEdge 5210 is around four times more expensive than the SnapServer but the Sun is king in terms of data throughput.
The Sun has great expansion potential in that you can attach up
to 42 drives, however Sun's largest drive was just 146GB at the
time of testing which reduces the total capacity to 6.1TB
raw.
The SnapServer 4500 at just over AU$7000 with 750GB of RAID 5
disk capacity certainly represents great value for money in terms
of cost per GB.
Not only was the 4500 inexpensive it was also surprisingly fast
in terms of data throughput, where the 4500 did lose some of its
shine was its expansion capability, which maxes out at 3.6TB, a
respectable figure to be sure but a long way behind some of the
other NAS tested.
Redundancy is also not the 4500's strong point but then again you
could buy a second 4500 and still have plenty of change. In the
end the SnapServer 4500's low cost, good performance, and feature
set are enough to carry it through to win the Editor's
Choice.
This article was first published in Technology & Business
magazine.
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