April 30th, 2007 by eugene
Seagate Savvio 15K.1
Proponents of a 2.5" form factor point out, however, that one could house three Savvio 15K.1s in the space required to mount just one Cheetah 15K.5, yielding a hugely superior spindle/volume ratio ; an array featuring three times the spindles in any given rack delivers vastly increased performance in the Savvio's target market: database- and transaction-server scenarios requiring the utmost in speed as requests pile up and create a high level of concurrency. A 16-megabyte buffer rounds out the drive's vitals.
In addition to higher performance, Seagate cites numerous other benefits related to the the 2.5" form factor. A physically smaller design translates into smaller, lighter parts and less power draw, in turn leading to lower operating temperatures. The smaller footprint also permits more efficient air flow, ultimately leading to lower overall operating costs that offset the significantly higher cost-per-gigabyte premium commanded by the family.
The following performance tests contrast the Savvio 15K.1 with the following contemporary 15K RPM Ultra320 units:
|Fujitsu MAU3147 (147 GB)||Previous-generation 3.5" enterprise-class unit|
|Hitachi Ultrastar 15K147 (147 GB)||Previous-generation 3.5" enterprise-class unit|
|Maxtor Atlas 15K II (147 GB)||Previous-generation 3.5" enterprise-class unit|
|Seagate Cheetah 15K.5 (300 GB)||Current-generation 3.5" enterprise-class unit|
Access Time and Transfer Rate
For diagnostic purposes only, StorageReview measures the following low-level parameters:
Average Read Access Time- An average of 25,000 random read accesses of a single sector each conducted through IPEAK SPT's AnalyzeDisk suite. The high sample size permits a much more accurate reading than most typical benchmarks deliver and provides an excellent figure with which one may contrast the claimed access time (claimed seek time + the drive spindle speed's average rotational latency) provided by manufacturers.
Average Write Access Time- An average of 25,000 random write accesses of a single sector each conducted through IPEAK SPT's AnalyzeDisk suite. The high sample size permits a much more accurate reading than most typical benchmarks deliver. Due to differences in read and write head technology, seeks involving writes generally take more time than read accesses.
WB99 Disk/Read Transfer Rate - Begin- The sequential transfer rate attained by the outermost zones in the hard disk. The figure typically represents the highest sustained transfer rate a drive delivers.
WB99 Disk/Read Transfer Rate - End- The sequential transfer rate attained by the innermost zones in the hard disk. The figure typically represents the lowest sustained transfer rate a drive delivers.
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The Savvio 15K.1's random read access time of 5.4 milliseconds narrowly sets a new record, besting the Atlas 15K II by the slimmest of margins. A 15,000 RPM spindle translates into an average rotational latency of 2 milliseconds; subtracting this figure from the Savvio's access time leaves an average seek of 3.4 ms, a full half-millisecond above Seagate's ambitious 2.9 ms claim. At 5.9 ms, the Savvio's average write access figure also rests among the fastest SR has recorded, tying that of the Atlas 15K II.
Constrained by a lower linear velocity in its outermost tracks when contrasted with traditional 3.5" form-factor drives, the Savvio turns in a maximum sequential transfer rate of 108 MB/sec, falling short of Seagate's own Cheetah 15K.5, a drive that clocks in with an impressive 135 MB/sec. Nonetheless, the Savvio's contemporary areal density allows it to surpass the maximum rates delivered by older 15K units. Rates decay to about 80 MB/sec when inner tracks are reached, a figure comparable to that of Seagate's latest 3.5" Cheetah.
It is important to remember that seek time and transfer rate measurements are mostly diagnostic in nature and not really measurements of "performance" per se. Assessing these two specs is quite similar to running a processor "benchmark" that confirms "yes, this processor really runs at 2.4 GHz and really does feature a 400 MHz FSB." Many additional factors combine to yield aggregate high-level hard disk performance above and beyond these two easily measured yet largely irrelevant metrics. In the end, drives, like all other PC components, should be evaluated via application-level performance. Over the next few pages, this is exactly what we will do. Read on!
StorageReview uses the following tests to assess non-server use:
StorageReview.com Office DriveMark 2006- A capture of VeriTest's Business Winstone 2004 suite. Applications include Microsoft's Office XP (Word, Excel, Access, Outlook, and Project), Internet Explorer 6.0, Symantec Antivirus 2002 and Winzip 9.0 executed in a lightly-multitasked manner.
StorageReview.com High-End DriveMark 2006- A capture of VeriTest's Multimedia Content Creation Winstone 2004 suite. Applications include Adobe Photoshop v7.01, Adobe Premiere v6.5, Macromedia Director MX v9.0, Macromedia Dreamweaver MX v6.1, Microsoft Windows Media Encoder 9.0, Newtek Lightwave 3D 7.5b, and Steinberg Wavelab 4.0f run in a lightly-multitasked manner.
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A drive not tuned for traditional desktop applications, the Savvio 15K.1 falls far short of numbers delivered by drives such as Maxtor's Atlas 15K II and Fujitsu's MAU3147, units from two houses that traditionally balanced their offerings for both single- and multi-user environments. At just 568 I/Os per second, the Savvio lags the category-leading Fujitsu by a whopping 53% margin in the SR Office DriveMark.
Results remain similar in the SR High-End DriveMark. While the MAU3147 continues to dominate at the top of the chart, Seagate's latest trails by a 40% margin.
Three decidedly different entertainment titles cover gaming performance in StorageReview's test suite.
FarCry, a first-person shooter, remains infamous for its lengthy map loads when switching levels.
The Sims 2, though often referred to as a "people simulator," is in its heart a strategy game and spends considerable time accessing the disk when loading houses and lots.
Finally, World of Warcraft represents the testbed's role-playing entry; it issues disk accesses when switching continents/dungeons as well as when loading new textures into RAM on the fly.
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Unlike single-user machines (whether a desktop or workstation), servers undergo highly random, non-localized access. StorageReview simulates these multi-user loads using IOMeter. The IOMeter File Server pattern balances a majority of reads and minority of writes spanning requests of varying sizes.
IOMeter also facilitates user-configurable load levels by maintaining queue levels (outstanding I/Os) of a specified depth. Our tests start with the File Server pattern with a depth of 1 and double continuously until depth reaches 128 outstanding I/Os.
Drives with any sort of command queuing abilities will always be tested with such features enabled. Unlike single-user patterns, multi-user loads always benefit when requests are reordered for more efficient retrieval.
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At lower concurrency levels, the Savvio 15K.1 delivers performance on par with that of the Maxtor Atlas 15K II... that is to say, about 20-30 IOps more than Seagate's own Cheetah 15K.5. Under heavier loads (16+ outstanding I/Os) the Savvio's smaller platters and lighter actuator assert felt as the Seagate pulls away from the Atlas 15K II to deliver the highest single-drive scores we have yet encountered.
Noise and Power Measurements
Idle Noise- The sound pressure emitted from a drive measured at a distance of 3 millimeters. The close-field measurement allows for increased resolution between drive sound pressures and eliminates interactions from outside environmental noise. Note that while the measurement is an A-weighted decibel score that weighs frequencies in proportion to human ear sensitivity, a low score does not necessarily predict whether or not a drive will exhibit a high-pitch whine that some may find intrusive. Conversely, a high score does not necessarily indicate that the drive exhibits an intrusive noise profile.
Operating Power Dissipation- The power consumed by a drive, measured both while idle and when performing fully random seeks. In the relatively closed environment of a computer case, power dissipation correlates highly with drive temperature. The greater a drive's power draw, the more significant its effect on the chassis' internal temperature.
Startup (Peak) Power Dissipation- The maximum power dissipated by a drive upon initial spin-up. This figure is relevant when a system features a large number of drives. Though most controllers feature logic that can stagger the spin-up of individual drives, peak power dissipation may nonetheless be of concern in very large arrays or in cases where a staggered start is not feasible. Generally speaking, drives hit peak power draw at different times on the 5V and 12V rails. The 12V peak usually occurs in the midst of initial spin-up. The 5V rail, however, usually hits maximum upon actuator initialization.
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Seagate's literature states the Savvio requires "at least 30% less" power than a typical 15K RPM drive, likely a comparison to either a same-capacity (73 GB one-platter) or same-platter-count (two, for a capacity of 150 GB) current-generation 3.5" drive. There's little reason to doubt the claim as the tests above demonstrate an advantage at idle of at least 40% in the Savvio's favor when put up against flagship 4-platter 15K designs. A 15K RPM drive's purpose in life, however, is to be constantly pounded with requests under a near-100% duty cycle. Under such loads, the Savvio's advantage increases, drawing less than half the power required by a 3.5" drive.
The Savvio consumes significantly less power upon startup than a 3.5" drive, though its advantage in overall 12V dissipation is not quite as impressive as the sustained dissipation the unit demonstrates under continuous operation.
Subjective Noise Impressions: The Savvio 15K.1's SAS interface precludes it from undergoing our standard objective sound pressure measurements. Subjectively speaking, however, the drive's acoustics, both at idle and seeking, set it worlds apart from traditional 3.5" 15K RPM units. Idle noise compares well with the quietest of 3.5" SATA drives as does a full-bore seek. Gone is the loud rumble traditionally associated with lightning-fast actuators, replaced by a whisper-quiet patter virtually inaudible above the noise floor that even a standard desktop PC sets.
The StorageReview.com Reliability Survey aims to amalgamate individual reader experiences with various hard disks into a comprehensive warehouse of information from which meaningful results may be extracted. A multiple-layer filter sifts through collected data, silently omitting questionable results or results from questionable participants. A proprietary analysis engine then processes the qualified dataset. SR presents results to readers through a percentile ranking system.
According to filtered and analyzed data collected from participating StorageReview.com readers, the Seagate Savvio 15K.1 is more reliable than of the other drives in the survey that meet a certain minimum floor of participation.
According to filtered and analyzed data collected from participating StorageReview.com readers, a predecessor of the Seagate Savvio 15K.1, the Seagate Cheetah 15K.3 , is more reliable than of the other drives in the survey that meet a certain minimum floor of participation.
Note that the percentages in bold above may change as more information continues to be collected and analyzed. For more information, to input your experience with these and/or other drives, and to view comprehensive results, please visit the SR Drive Reliability Survey.
In the end, the 2.5" Savvio 15K.1 does make good on the firm's claim that drive delivers at least 10% more IOps at various concurrency levels than comparable 3.5" drives. As a result, the 15K.1 lays claim to the title of "world's fastest drive" when it comes to enterprise-level multi-user applications.
Just as importantly, however, the drive meets its power requirement claims with aplomb and as a result significantly changes the power and cooling equations and, ultimately, the IOps-per-rack landscape.
These improvements, of course, come with a large financial outlay; if the disparity between the 10K Savvio and Cheetah is any indication, the Savvio 15K.1 will command a hefty premium when it comes to obtained gigabytes-per-dollar. Even so, the 15K.1 finds a niche where the ultimate in speed or IOps/volume is paramount, and, just as importantly, fleshes out the burgeoning 2.5" enterprise storage paradigm.