- Install A Solid State Drive In Your Notebook
- WD and Toshiba Join the 320 GB 2.5" HDD Club
- 2.5" HDD Galore: Samsung, Seagate, Toshiba
- Samsung, Ridata SSD Offerings Tested
- Momentus 5400 FDE.2: Data Encryption On-a-Drive
- Samsung Spinpoint F1 HDDs: New Winners?
- Mtron SSD 32 GB: Performance with a Catch
- TravelStar 7K200 and 5K250 Beat the Band
- HyperDrive 4 Redefines Solid State Storage
- The Terabyte Battle
Source: Tom's Hardware – Keywords: HDD, SATA, VelociRaptor
Topics: Build Your Own
Syndication:
Hard Drive Performance Basics
While the recording technology defines the storage capacity, spindle speed is the most important parameter that influences performance. Not only will high RPMs provide the best data transfer rates possible (expressed in Megabytes per second), but they also shorten average access time (expressed in milliseconds). Here we have to differentiate between the seek time, which manufacturers usually refer to, and to the average access time, which includes locating data, positioning the heads above the appropriate track and waiting for up to a full platter rotation before the required data is accessible by the heads. This idle time is referred to as rotational latency. Obviously, faster spindle speeds will not decrease the seek time, but they very well reduce the access time, as rotational latency will be much lower.
Seek time and access time also depend on a drive’s performance when relocating heads from one platter surface position to the next. Arm acceleration performance and break performance come into the equation; both have physical limitations and this movement contributes to a drive’s noise level, as do spindle motor and friction noise. Although hard drives are sealed, the inside is sealed by the use of small filters. Since an air cushion is needed to have the heads flow above the surface (aerodynamics comes into the equation as well) they do not operate in a vacuum. Performance hard drives for the enterprise segment aren’t optimized from an acoustic standpoint, so they can be easily heard; especially when there is a lot of arm movement going on.
All hard drives come with cache memory, which is used to store read or write data based on complex algorithms. Most drives have 8 or 16 MB cache; some models go up to 32 MB. The cache memory capacity really isn’t a big deal as long as you have some. In a very simple example, a hard drive may continue reading more data into the cache memory even after the requested data has been read, because there is a chance that the following sectors may be requested soon.
All modern hard drives utilize either the Serial ATA (SATA) or the Serial Attached SCSI (SAS) interface. Serial ATA is based on the good old parallel UltraATA protocol, while SAS builds up on the Small Computer System Interface. Both SAS and SATA use the same connectors and offer the same bandwidth (150 or 300 MB/s), but SAS is fully SATA compatible, as it can tunnel the SATA protocol. They both also support similar feature sets such as Native Command Queuing (NCQ), which the drive utilizes to analyze and reorder incoming or pending commands in an effort to process them with the highest efficiency possible. SAS still is more sophisticated, as it allows drives to run on two physical connections for the sake of performance or redundancy.
Related article: Understanding Hard Drive Performance
Drive Energy Efficiency Basics
Physical movement requires energy; hence it doesn’t come as a surprise that high RPM hard drives typically require more power than slower models. However, this also depends on the drive generation, on the platter diameter and on the platter count. A 2.5" 15,000 RPM hard drive with only two platters may very well consume less power than a larger 3.5" 10,000 RPM drive, which utilizes four or five platters. If you compare drives within similar generations (e.g. 2008 hard drive models), it is safe to assume that a high capacity 3.5" terabyte hard drive will always consume more energy than a smaller-capacity 3.5" single platter drive at 250 or 320 GB, and that higher RPMs will require more energy as well.
While PCs are increasingly being evaluated from a performance per Watt standpoint, the hard drive industry must also consider capacity per Watt. 3.5" hard drives turned out to be ideal in this benchmark, as they currently provide up to 1 TB of storage per drive (Serial ATA models) at power consumption of 3-15 W. Smaller capacity, single-platter versions may provide lower power consumption, but at the same time they’re inferior when it comes to capacity per Watt.
Lastly, the drive’s interface contributes to power consumption. We found that parallel interfaces such as UltraATA or SCSI were generally more energy efficient, SATA shows differences whether it’s running on 1.5 Gb/s or 3.0 Gb/s. The faster link speed takes its toll by adding some 0.3-0.5 W to a drive’s total power consumption. While the old Raptor-X at 150 GB wasn’t bottlenecked using SATA/150, the VelociRaptor gets close to the limits of this interface by reaching almost 125 MB/s. Since there is a certain protocol overhead, which becomes obvious when looking at SATA/150 drives that typically max out at 126 MB/s, introducing SATA/300 was an absolute necessity.
- Previous page Hard Drive Basics
- Next page Western Digital VelociRaptor VR150...
- 1 / 4
- Next
-
#2 - A very well written article. I've noticed an uptick in the quality of articles of late. Kudos again.
#3 - A very nice HDD. Something I may definitely look at adding to my system.
http://www.newegg.com/Product/Prod [...] 6822136218
Seagate 7200.11 (if they can work out their doa prob):
http://www.newegg.com/Product/Prod [...] 6822148316
A few of samsung's F1 spinpoints...
they are all pretty close, especially seagate at 114mb STR, 60 low and around 100 average across 320 gigs.
A 150 gig drive that is just a bit higher is not so awesome, and yes I know seek times, IO and all that matter too. Do you really thonk the new raptor is gonna be 90 bucks like these, I sure don't.
If they at least have a 320 same performance, or the performance was closer to 150 (as in a larger 3.5 platter), then sure, but it's sad considering a 7200 is almost passing them ALREADY.
You could say you don't think it's worth the cash, I have no problem with that, but it sounds a lot like sour grapes to me.
It has twice the storage space of the previous top model.
It has better benchmark results.
It runs cooler way cooler.
That IcePack is perfect for mounting behind front intake fans(improved airflow).
I'd want 1 over any 1TB drive. The price is also quite reasonable for a Raptor.
I'd call that progress in every way.
There's just no pleasing some people.
I wonder why I/O performance isn't as good as the SAS drives even though it has faster read/write speeds and latency. Could this be fixed with firmware?
| rodney_ws wrote : Honestly, who was expecting the next Raptor to be a 2.5 inch drive? I know it's in a 3.5 inch enclosure, but you just know the guys at Alienware are trying to figure out how one of these is going to work in a laptop. |
Notebook HDs only need 5V and the velociRaptor needs both 12V and 5V. I'm not saying it can't be done.
- I get 30%+ of performance increase compared to my 1TB drive (yah, 10EACS)
- I get 300gb for $300, I already have 1000gb for $300
- I can get 640gb instead of 300gb with little speed decrease but it will cost $130.
So 30%+ speed increase equals almost 5x price increase? My wallet thinks otherwise... But thats my wallet, if your wallet says otherwise, I think you'll be happy with the new HDD from WD
| royalcrown wrote : It's not sour grapes...it's spoon feeding us tiny bumps and calling it amazing that gets me...it's better, but amazing or wow or making a big deal about an incremental increase is just hyping it up, when it's not that big of a step up. |
Hard drives have to live within the laws of physics and current technology. Maybe you know of some way to get a 200% improvement. By all means share it with us.
- 1 / 4
- Next
-

