A flurry of SATA (serial ATA) storage solutions is quickly pushing parallel ATA out of the market. Even though SATA is faster, more flexible, and more scalable than ATA, not to mention equally affordable, the protocol still fights a perception of inadequacy for critical business applications.
That perception is understandable, because of SATA's ancestry, and also because of the protocol's extreme adaptability, which extends from enterprise-grade to home-user solutions (please see the sidebar for an interesting example of the latter). However, as storage managers become more familiar with SATA controllers and drives, those doubts will be put to rest.
I recently tested SATA RAID controllers from 3ware Inc., Adaptec Inc., and LSI Logic Corp., three controllers serving different sets of storage requirements. All three offer top-notch features and leave enterprise users with little or nothing to be desired. Furthermore, these controllers support outstanding aggregate transfer rates, limited only by the performance capabilities of the attached drives (as verified in my tests). You also can easily add and manage large amounts of storage to your servers.
But there are important differences. If you're looking for maximum storage capacity, 3ware's Escalade provides eight ports at an attractive price and supports all major RAID levels. For an easy and inexpensive upgrade consider the budget-friendly Adaptec 1210SA. You'll like its powerful management tools, but don't expect it to handle more than mirroring and striping on its two ports.
And finally, LSI Logic's MegaRAID 150-4 extracts a slightly higher cost per port, but offers numerous management applications and more accurate configuration parameter tuning. It's the only controller of the three to provide drivers for Novell NetWare servers.
The 3ware Escalade 8500 has already been deployed in several mid-tier storage arrays, including recent products from vendors such as Iomega and Okapi Software. In addition to the eight-port model I reviewed, 3ware also offers four- and 12-port versions of the controller, the latter setting a capacity record for SATA RAID cards that is unchallenged.
If your servers have enough drive slots, installing the eight-port Escalade can add terabytes of space you can easily group in multiple logical volumes, choosing the RAID architecture that best fits the application. To configure the RAID level for the Escalade, you simply invoke the card's BIOS-contained configuration utility at boot time. Intuitive commands select drives for a new logical volume, define hot spares, and choose the striping size where appropriate.
Two minor annoyances: the Escalade card precedes motherboard-embedded controllers in the boot sequence, and it lacks a permanent setting for not loading the BIOS, which on my test machine meant using a key sequence at every restart to boot properly.
But all in all, I found the Escalade easy to use and configure. A browser-contained administrative GUI, 3DM, monitors the status of the controller and automatically generates e-mail warnings of errors. In addition, 3DM automatically schedules basic maintenance tasks such as scanning drives for errors or verifying the health status of a logical volume. You can instruct 3DM to refuse connections from other computers, which provides a reliable, if drastic way of preventing unwanted access.
Trimmed for two
Adaptec's recently released 1210SA controller offers only two ports, limiting the possible configurations to simple mirroring or striping over two drives. Nevertheless, the management tools are impressive. The included CD boots Linux and loads a menu offering choices such as invoking a browser-based management tool, creating a diskette for the controller's drivers, or reading the documentation.
Moreover, the 1210SA RAID configuration can be set not only from the BIOS utilities but also online from Adaptec's Storage Manager browser-based GUI. The clear advantage of online configuration of logical volumes is shortened downtime for that server, an option 3ware's 3DM limited online management features do not provide. Needless to say, you cannot modify online logical volumes that contain the OS or other running software.
Moreover, Storage Manager uses an SSL connection, which provides more flexible management access control from other computers than the simple "local only" restriction of 3ware's 3DM. On the other hand, unlike 3DM, Storage Manager doesn't offer the option of automated e-mail warnings for malfunctions, but at installation time you can activate an SNMP module and capture errors or other data using that protocol.
I liked the comprehensive set of features offered by Storage Manager, although they may be overkill for a two-port controller. Of course, Adaptec will no doubt provide the same tools for managing upcoming four-port and eight-port models of the controller. Moreover, Storage Manager can administer multiple controllers, an option I found very useful for monitoring the two cards sent by Adaptec.
Made for managing
The four-port MegaRAID 150-4 controller is the latest addition to LSI Logic's SATA family, which also includes a six-port model. The 150-4 is so new that, to make the editorial deadline, I could not wait for a setup CD; I received drivers, the Power Console management software, and an updated BIOS via e-mail attachment.
Nevertheless, the installation was quite smooth. LSI Logic offers not one but two boot-time utilities that essentially deliver the same functionality, although the WebBIOS tool has a slick, browser-inspired look. However, you can skip both, and go straight to Power Console Plus, the online management tool, to create new logical volumes.
Despite the confusing number of similar tools (a fourth extends management to non-Microsoft operating systems) LSI Logic offers the most granular array settings in this group. For example, using Power Console Plus, I dynamically adjusted the cache settings for a logical volume (I noticed an immediate jump in performance on Iometer's reports running in the background). In addition, Power Console Plus provides access to the same tool from different machines to prevent intrusions, an option that restricts remote access to view-only.
Power Console Plus is the only management tool in the group that can simulate a disk failure, which is extremely useful to test recovery from hardware errors. For example, after simulating the failure of a drive in a RAID 5 array, I immediately saw the recovery process grab a hot spare and begin rebuilding the drive, while access to the array was unaffected. It's difficult not to like the MegaRAID and its management features, but LSI Logic ought to weed out the redundant tools.
The most common enterprise deployment scenario for SATA RAID controllers will be to update existing servers for additional capacity and performance. In most cases SATA drives and controllers won't arrive in new servers but will be installed on machines currently in use.
Therefore, ease of setup was one of my evaluation's most important criteria. For each controller, I noted the difficulty or ease of the setup process, assigning higher marks to solutions least disruptive to the administrative routine.
I considered management capabilities equally important. All three solutions reviewed demonstrated strong administration features. I assigned slightly higher scores to the Adaptec and LSI Logic solutions, whose browser-based configuration capabilities simplify on-going management. Adaptec and LSI Logic also scored higher in interoperability, due to 3ware's annoying manual intervention requirement during bootup.
Performance is part of the design with SATA, and all three controllers' data transfer capacities outstripped those of the test drives. Because of this, I couldn't hope to compare the total capacities of the controllers, but I did use the I/O performance analysis tool, Iometer, to gauge transfer rates on individual ports and verify that each was performing properly.
To obtain comparable performance measurements for each controller, I installed each card, sequentially, on the same server (an HP ProLiant ML350 running Microsoft Windows 2000 with Service Pack 3). For each controller, I set identical logical volume in striping mode, using the same physical drives across configurations.
Using the Iometer load simulator, I ran the same scripts on each configuration, noting differences in data transfer rates and CPU utilization and comparing them against Windows Performance Monitor statistics to double-check for accuracy. To test aggregate transfer rate, I connected drives to each controller port, again simulating read and write load with Iometer.