Each of the 16 disk arrays we tested, with a few minor exceptions, consisted of a case enclosing an array of five half-height 2-GB drives, an array controller board or comparable hardware, a power supply and fan, and a configuration utility and LCD panel that lets you select the RAID level and make other array configuration selections. Most products provided some additional level of hardware redundancy, such as a sixth drive to be used as a hot spare, a second power supply, fan, controller, or some combination of these. All these arrays were designed to survive a single-drive failure.
For RAID 5 testing, we connected each array to a file server running Microsoft Windows NT 3.5 and formatted the array as one large drive (the formatted capacity of these arrays averaged about 8 GB). We ran a series of auto
mated low-level disk tests that were designed to simulate the real-world conditions found on a typical disk subsystem connected to a PC file server.
The
Best Overall winner
is Digital Equipment's StorageWorks RAID Array 230 Subsystem. The StorageWorks had the fastest performance and the widest range of features, including redundant and hot-swappable drives, power supplies, fans, a drive for a hot spare, and a write cache with battery backup. The three-channel controller is designed to install in a PCI-based file server and can support two additional enclosures for up to 90.3 GB of storage. The StorageWorks' Online Management Utility for NT does a good job of giving you an exact and readable status during a drive failure and rebuild operation. The StorageWorks is also one of the least-expensive units we tested.
The
second- and third-ranked products
from Mega Drive and Storage Solutions, respectively, had virtually identical overall scores. Of the two, the Storage
Solutions' Raca-Ray CM2+ was faster and had the best multithread performance score of any array we tested. The Raca-Ray's speed comes in a not-so-glamorous package; its drives sit in open, trackless bays, making them somewhat awkward to put in and pull out. The Raca-Ray does not support a spare drive, but it does have a user-friendly monitoring utility called Raca-Lert for Windows (see the article "Honorable Mentions"). You can also expand this product to a three-rank unit for a total of 15 drives.
The Enterprise E-8 PCI from Mega Drive Systems is an attractively priced unit with good performance, features, and usability. The Enterprise is designed to let you mix and match different types of storage media, including half- and full-height drives, half-height optical drives, and half-height DAT (digital audiotape) modules. (Mega Drive reports that a popular configuration with its customers is an array with two mirrored full-height 9-GB drives.) The Enterprise has a dual-channel Mylex PCI controller with
an HRI (Hardware RAID Controller Interface), which reports fan and power-supply failures to the file server. Our one complaint was due to the flimsiness of the door on the Enterprise's drive bays. Because the door doubles as drive tracks when you push the drives into the enclosure, its design sometimes made it difficult for us to seat drives properly. According to a company representative, Mega Drive has already retooled to correct this glitch.
Placing fourth and fifth
, with nearly identical overall scores, were the CR12-RAID by Conner Storage Systems and the FlashDisk SCSI by Winchester Systems. The CR12-RAID uses a dual-channel controller, supports redundant hot-swappable drives, power supplies, and fans, and can be configured with up to 12 drives. It also has graphical monitoring utilities for NT and NetWare and a five-year warranty on both its drives and subsystem. The Winchester FlashDisk SCSI offered better overall performance than the CR12-RAID but is priced considerably higher
than the other top five subsystems. The FlashDisk is sold in configurations with up to 128 GB of storage capacity.
If you're on a budget, two of our previously mentioned winners -- the Digital StorageWorks and the Mega Drive Enterprise -- are priced at under $13,000. At $10,255, Procom Technology's LANForce-5 was the lowest-priced unit tested here. The LANForce-5 offers full redundancy and hot-swapping components -- drives, power supplies, fans, and controllers, as well as a sixth drive for a hot spare -- but its performance was below average. The company reports that a new high-performance controller will be available for this product this summer.
In analyzing the performance of these subsystems, it's apparent that RAID controllers play a major role. Three of
the top-ranked arrays
-- Digital, Mega Drive, and Conner -- use various models of controller from Mylex. It's interesting to note that write-caching didn't determine who made our top-five list. As neither the Raca-Ra
y nor the CR12-RAID had battery backups, their performance scores were based on their "write-cache off" results, and both still made the grade. As for reliability, participating vendors quoted the MTBF (mean time between failures) of the individual drives in these arrays as ranging from 500,000 to 1,000,000 hours. All the arrays we tested successfully withstood a simulated single-drive failure. Our tests did not measure the relative drop in performance that these arrays would experience while in rebuild mode (also known as degraded mode). On many arrays, when configuring the array, you can determine the rate of rebuild; the faster the rebuild, the more current server performance is slowed.
Weighting for Best Overall
PERFORMANCE 50%
FEATURES 25%
USABILITY 25%
Disk Arrays
BEST OVERALL:
Digital StorageWorks RAID Array 230 Subsystem
The Digital StorageWorks RAID Array 230 Subsystem w
as the clear
winner in this category. Its fast performance and wide range of
features, including redundant and hot-swappable drives, power
supplies, fans, a sixth drive for a hot spare, and a write cache
with battery backup, placed it well above the other subsystems.
Its Online Management Utility for Windows NT provides an exact
and readable status during a drive failure and rebuild operation.
OVERALL
EVALUATION
PRICE SCORE FEATURES USABILITY
===========================================================================
BEST DEC StorageWorks RAID Array $12,183 7.97 **** ****
230
RUNNER-UP Mega Drive Enterprise $11,900 7.06 *** ****
E-8 PCI
RUNNER-UP Storage Solutions $13,595 7.05 ** ***
Raca-Ray CM2+
RUNNER-UP Conner CR12-RAID $16,593 6.56
*** ***
RUNNER-UP Winchester Systems FlashDisk $19,737 6.55 *** **
SCSI
PERFORMANCE INDEX
----------------------
SINGLE- MULTI-
OVERALL THREAD THREAD
=========================================================================
BEST DEC StorageWorks RAID Array 230 7.61 7.77 7.45
RUNNER-UP Mega Drive Enterprise E-8 PCI 6.28 7.60 4.96
RUNNER-UP Storage Solutions Raca-Ray CM2+ 7.17 6.08 8.26
RUNNER-UP Conner CR12-RAID 5.47 4.69 6.26
RUNNER-UP Winchester Systems FlashDisk SCSI 6.18 6.11 6.26
KEY:
Ratings from 1 to 4: * is the lowest; **** is the highest.
Disk Arrays
LOW-COST:
Digit
al StorageWorks RAID Array 230 Subsystem
With its test-configuration price of $12,183, the Digital
StorageWorks RAID Array 230 Subsystem is an excellent value. For
this price, you get five drives and a sixth spare drive, a second
power supply and fan, battery-protected write cache, monitoring
utilities for Windows NT and NetWare, a one-year on-site warranty
and a five-year warranty on the disk drives. Offering many of the
same features is the $11,900 Mega Drive Enterprise E-8 PCI. The
Enterprise has a standard two-year warranty and comes shipped with
a DAT (digital audiotape) drive module in addition to its five-
drive array and one spare drive.
OVERALL
EVALUATION
PRICE SCORE FEATURES USABILITY
=============================================================================
BEST DEC StorageWorks RAID Array $12,183 7.97
**** ****
230
RUNNER-UP Mega Drive Enterprise $11,900 7.06 *** ****
E-8 PCI
RUNNER-UP Procom LANForce-5 $10,255 5.97 *** ****
RUNNER-UP Raidtec FlexArray FX $11,195 5.61 * ****
RUNNER-UP DPT SmartRAID Subsystem $12,615 4.94 ** ****
PERFORMANCE INDEX
----------------------
SINGLE- MULTI-
OVERALL THREAD THREAD
==============================================================================
BEST DEC StorageWorks RAID Array 230 7.61 7.77 7.45
RUNNER-UP Mega Drive Enterprise E-8 PCI 6.28 7.60 4.96
RUNNER-UP Procom LANForce-5 3.91 4.67 3.15
RUNNER-UP Raidtec FlexArray FX 4.24
4.34 4.14
RUNNER-UP DPT SmartRAID Subsystem 2.08 2.59 1.57
KEY:
Ratings from 1 to 4: * is the lowest; **** is the highest.
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From left: Winchester Systems' FlashDisk, Mega Drive's Enterprise, Conner's CR12-RAID, Storage Solutions' Raca-Ray, and Digital's StorageWorks.
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Best Overall Disk Arrays
