Put to the Test: The Incredibly Shrinking Hard Drive

Seagate claims its 2.5-inch Savvio hard drives triple the data density in your storage rack. Can something so small really do such a big job?

June 10, 2004

5 Min Read
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Less Space, More Data

Moving toward smaller hard drives makes good business sense. A recent IDC study shows that in larger cities, data-center floor space costs $500 to $1,000 per square foot. To minimize the need for sprawling data centers, companies must start looking at smaller, more efficient ways to use their available space. Seagate's Savvio drives are leading the next revolution in enterprise data storage.

Today, more than 1.5 million TB (1.5 exabytes) of information are produced and stored worldwide each year, according to a recent study by the University of California-Berkeley School of Information Management and Systems, titled "How Much Information?" That figure is projected to grow more than 55 percent every year. A typical rackmount enclosure for 3.5-inch drives holds up to 15 drives and takes up 3U of rack space. By comparison, you can fit 30 2.5-inch drives into an enclosure that requires only 2U. A standard 44U rack stocked with 2.5-inch drives can hold 48 TB of data, compared with only 15 TB when the larger drives are used. That equates to 660 individual drives in a single rack versus the 210 drives currently possible.

Conventional servers and blade servers alike can use the 2.5-inch hard drives. Now, 1U servers can be configured with up to six hard drives, rather than just two, to expand local storage capacity and make options like RAID 5 feasible. Compared with mirrored drives, such expanded RAID options boost reliability without sacrificing half the server's storage capacity.

SeaGate's Savvio

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Furthermore, blade servers no longer need to rely on 2.5-inch drives designed for notebook computers. Such drives lack the speed and performance of the new Savvio drives and are not designed to run 24/7/365. Their spindle speeds, which range from 4,200 rpm to 7,200 rpm, compared with Savvio's 10,000, create higher seek times--12 ms, on average. Laptop drives also have a lower MTBF rating, typically around 300,000 hours; Seagate rates Savvio at 1.4 million hours. (Laptop hard drives have higher shock ratings than the Savvio drive--up to 225 Gs of shock, compared with Savvio's 60 Gs while operating. But that makes sense, considering notebooks' greater mobility.)

The 2.5-inch drives have smaller platters and motors than 3.5-inch models. The platters use a shorter, stiffer drive actuator arm, which speeds seek times and boosts durability over traditional actuator arms. The new Seagate Savvio drives' 4.1-ms seek time is 15 percent faster than the 4.7 ms of an equivalent 3.5-inch drive.

These smaller drives also consume less power than the larger ones: as little as 5 watts when idle and a paltry 8 watts while accessing the drive. That's half the power a similar 3.5-inch model needs.

Blazing a Trail

Seagate is shipping its first Savvio drives in a single-platter 36-GB and a dual-platter 73-GB model. We tested the 73-GB model and an equivalent drive, the 3.5-inch 73-GB Seagate Cheetah, both running at 10,000 rpm, with the Iometer 2003.12.16 test suite in our Green Bay, Wis., Real-World Labs®. Seagate sent us two arrays with the Savvio drives in them--one a tower configuration and the second in a rack--so, besides comparing them with the Cheetah, we looked for performance differences resulting from the enclosures. We tested 14 drives in each of the arrays configured as a logical RAID 5 using Windows Disk Manager. All tests used a 10-GB test file that the Iometer generated and copied to each array.The Savvio drives were faster than 3.5-inch Cheetah counterparts in Iometer's simulated database test, as well as in raw I/O operations per second. There were negligible differences in all the tests between the two Savvio arrays. However, the Cheetah beat the Savvio in the sequential read/write tests when the file-request size was smaller than 2 MB. The smaller the request size, the greater the gap between the two types of drives. The Savvio drive arrays seem especially suited for database applications and other areas where sustained sequential reads from the drives aren't needed.

At 111 mm long by 70 mm wide by 15 mm high, the Savvio drive is 70 percent smaller than 3.5-inch drives. And at 8 ounces, it's less than one-third the weight. Initially, only the U320 SCSI and 2-Gbps FC interfaces will be available. However, a Serial Attached SCSI (SAS) version with a 3-Gbps point-to-point integrated connector is slated to ship late this year. Seagate hasn't announced any SATA drives. Suggested retail pricing for the Fiber Channel model is $945. The SCSI model is priced at $925. In comparison, a 73-GB Cheetah drive is $699. (See a table listing features of the Savvio and Cheetah drives).

Eric Fleming is a network administrator for KI, a furniture manufacturer based in Green Bay, Wis. Write to him at [email protected].

The test bed for our examination of Seagate's new Savvio 2.5-inch hard drives included a Dell 2650 server with dual 2.6-GHz Xeon processors running Windows 2000 Server SP4. The server had a QLogic 2342 dual-channel HBA adapter installed for connectivity to a Cisco MDS-9216 Fibre Channel switch.

Our Iometer tests gauged the performance of the two types of drives by utilizing the following: 64-Kbps linear read test; 64-Kbps linear write test; 1-MB linear read test; 1-MB linear write test; 2-MB linear read test; 2-MB linear write test; IOps; NWC Generalized Custom Test; and a database-access test. For all linear read and write tests, we set the read/write distribution to 100 percent read and 100 percent write. Random/sequential distribution was set at 100 percent sequential. Our IOps test had a 512-byte transfer request size, and was also set to 100 percent read and 100 percent sequential.

Hard Drive Performance Analysis

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The NWC Generalized Custom Test had transfer request sizes of 512 bytes with 33 percent access distribution, 2 KB with 34 percent access distribution and 64 Kbps with 33 percent access distribution.

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