2026-04-26

Sustained Data Transfer Rates For SCSI Hard Drive

DATARECOVERYUNION.COM07 mins

Data Transfer Rate Many factors contribute to disk drive performance. One useful measure is data throughput rate or sustained transfer rate. In general, higher data transfer rates from the disk to the computer lead to improved system performance. Data transfer rates are often quoted within the “Specifications” section of the product manuals. Yet it is important to realize that controller overhead, cable quality and termination issues (on older SCSI products) are major factors that affect sustained data transfer rates.

The following specifications are from an older SCSI hard drive. These numbers are used for example, but the same calculations apply to ATA drives. Notice that the internal data transfer rate is listed as sustained, while the external data transfer rate is listed as burst.

INTERNAL DATA TRANSFER RATE (Megabits/sec.)____194 to 340 (sustained)

EXTERNAL DATA TRANSFER RATE – Buffer to SCSI controller (Megabytes/Sec)___Ultra160/m 160 MB/Sec. (burst)

As there are 8 bits to a byte, and 8 Megabits (Mb) to a Megabyte (MB), we divide 194 Mb’s/sec. by 8 to get 24.25 Megabytes/sec. The drive should sustain a transfer rate of 24.25 MB/sec. from the drive platters to the read/write heads, even under the worst possible conditions. The lower number of the range measures data transfer from the inner diameter of the drive platters, where there are the least amount of sectors per track. The higher number of the range measures data transfer from the outer diameter of the drive platters, where the number of sectors is higher per track. Using the higher number of the range (340), the result is 42.5 MB/Sec.

We then have a data rate in Megabytes, of 24.25 to 42.5 MB/sec. Since this is an ‘internal’ data transfer rate, consider it as the raw data rate. Some of this internal rate is lost when translating to the user data rate, because this raw data includes coding overhead that adds length to the user’s data. Add a 25% allowance (more for some drives) for system overhead. In the case of this older SCSI drive, the overhead is approximately 30%. The sustained (user) data rates are actually listed at 17 to 29 MB/Sec. For drives where only the internal data rate is listed, the formula ([Internal rate in Mb/8] x .75 = Approx. data rate in MB ) is used to develop an approximate user data rate.

Most of the time you won’t be getting the lowest sustained transfer performance or the highest, so we should find an average. Using the average of the sustained transfer rates ([17+29]/2=23), you receive an expected average sustained data transfer rate of 23 Mbytes/sec.

It’s very important to realize how these numbers are presented. The internal data rate shown here is expressed in Megabits/sec, the user data rate is written in Megabytes/sec. Certainly, we can tell you, assuming your SCSI (or ATA) subsystem is configured correctly, what your expected sustained transfer rates should be. In this case, a sustained transfer rate of 17 MBytes/sec. to 29MBytes/sec. is acceptable. Your transfer rates may be higher–or lower.

If your sustained user data rates are lower than expected, this indicates a bottleneck in the system. A failing device, improper configuration, and termination issues are leading causes for poor performance. Be aware that transfer rates can be reduced by several issues–poor quality cables, improper cable routing (causes signal reflection), SCSI Single Ended devices on an LVD SCSI bus, host limitations and more.

While you might expect to see 320 MB/sec. transfer from your SCSI Ultra 320 devices, or 300 MB/sec. from a SATA drive, know that these specifications are the burst rate–what the drive’s cache memory buffer can process under the absolute perfect combination of drive, cable, and hard drive controller conditions. Even ambient temperature affects transfer rates. This is not the sustained transfer rate of the drive. It’s what the input/output subsystem is capable of handling. For hard drives, sustained transfer rates are an important benchmark. Only when combining several high-speed drives together (in a performance RAID array), does one approach ‘bus saturation’ speeds.

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WD My Passport AV 320 GB Portable External Media Drive

DATARECOVERYUNION.COM16 mins

WD My Passport AV 320G Portable External Media Drive WD® introduced its new My Passport™ AV portable media drives. Designed specifically for video storage and playback, the new My Passport AV portable media drives deliver a plug-and-play experience for digital media enthusiasts. Available now at select retailers and WD’s online store, the My Passport AV portable media drive is offered with 320 GB of capacity.

A large and increasing number of game consoles, camcorders, TVs, DVRs, Blu-ray players and media players, including the WD TV® Media Player family, allow consumers to connect a USB drive and play the multimedia content from the drive on an HD TV. The My Passport AV portable media drive is designed to meet the requirements of this demanding video streaming environment. It delivers the formatting and low-power consumption that assures out-of-the-box compatibility with many leading CE (consumer electronics) devices.

WD worked to ensure that the My Passport AV portable media drives operate seamlessly with the Direct Copy feature offered in Sony’s new Handycam® video recorders. Direct Copy lets Handycam users offload and archive HD video directly to a My Passport AV portable media drive without a computer, creating room to shoot more HD videos when their Handycam hard drive becomes full.

Consumers can then play back their stored videos using Sony’s latest Blu-ray players or any of the WD TV media players by just connecting the My Passport AV portable media drive via the USB port on these players. Specific Handycam and Blu-ray model compatibility information is available on the WD Web site.

With its small footprint, the My Passport AV portable media drives are designed to fit neatly in a home entertainment center. The included stand and extra long cable makes it easy to position the drive neatly in entertainment centers, maximizing the airflow and minimizing heat around the drive.

“With more and more devices capable of generating and playing back HD video – camcorders, Blu-ray players, game consoles – portable hard drives are the best solution for this 8 GB-per-hour capacity-intensive content. The My Passport AV portable media drive is optimized for a better digital video experience with a growing list of consumer electronics, starting with Sony’s latest camcorders and Blu-ray players,” said Dale Pistilli, vice president of marketing for WD’s branded products group.

Price and Availability
The New My Passport AV portable media drives feature a 2-year limited warranty and are available now at select retail stores and WD’s online store. MSRP for the My Passport AV portable media drive with 320 GB is $109.99 USD.

This item has not yet been released on amazon.com. You may pre-order it now (at a low price of $79.99) and they will deliver it to you when it arrives.

My Passport AV Compatibility
My Passport AV portable media drives are formatted FAT321 and are compatible with Windows® XP, Windows Vista™, Windows 7, Mac® OS X® and Apple’s Tiger®, Leopard®, and Snow Leopard®. My Passport AV portable media drives utilize the same drive technology found in WD AV drives inside leading cable and satellite set-top boxes and DVRs (digital video recorders) around the world.

The My Passport AV portable media drives are compatible with the following devices:

* WD TV family of media players;
* 2010 and later Sony camcorders with Direct Copy functionality;
* Sony 2010 Blu-ray Disc Players including BDP-S370, BDP-S470, BDP-S570;
* Sony 2010 Blu-ray Disc Home Theater Systems including BDV-E370, BDV-E570;
* JVC LT-32P689 television;
* Samsung® LN32A550 television;
* Phillips® 42PFLA332D television;
* Microsoft Xbox 360® (compatible with the USB media playback feature); and,
* Sony PlayStation®3.

For a complete list of devices compatible with the My Passport AV portable media drives, please visit the WD Web site. A product specification sheet and photos of My Passport AV drives are available on the company’s Web site at http://www.westerndigital.com/MyPassportAV.

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32MB VS 16MB Cache

DATARECOVERYUNION.COM02 mins

I’m building a new rig, and need to know if theres really any noticeable, real-world performance difference between a 500GB hard drive with 16MB cache or a 500GB drive with 32MB cache. both would be running on Sata III 6GB/S.  16MB vs. 32MB cache – any difference?

16mbVs32mb

Of all the factors that affect a drive’s performance, cache is by far the least important. The most important factors are the spin rate (RPM) of the drive and the platter density. More spins per second = more data per second, and higher platter density means more data per spin = more data per second.

Cache is important, but once you get beyond a certain amount it doesn’t really give you any better performance. Since cache memory is cheap, all the manufacturers include enough of it to optimize the performance of the drive. As a result, differences between one drive and another don’t really make a noticeable real-world difference.

In fact, the most common reason for different cache sizes is because the platter density is different and so the drive needs more cache to hold “x” tracks worth of data. In this scenario the drive with more cache will perform better, but it’s because of the higher platter density, not because of the extra cache.

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Kingston sms200s360gmsata solid state drive cannot be recognized and the recovery is successful

DATARECOVERYUNION.COM02 mins

Case:Before the Spring Festival, the Data Recovery Center continued to receive customers’ solid -state hard drives. The model: SMS200S360GMSATA, the failure cannot be recognized.These solid -state hard disks are used by customers of some business elites. There are important company data in it, and hard disks have hardware encryption functions. Solution:After the underlying analysis and…

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Cables for FreeAgent GoFlex Drives

DATARECOVERYUNION.COM05 mins

Seagate GoFlex drives are designed to be flexible; therefore the cable module is interchangeable with several interfaces. Below are examples of these cables.

Common questions about FreeAgent GoFlex cables:

Q: How many times can I plug and unplug my cable?
A: The design for the connector to the drive and the cables ends have been tested to 5,000 cycles similar to past USB products.

Q: Can I use more than one cable on a drive?
A: Cables can be changed after safely removing the drive from the computer; however you cannot use more than one cable at a time.

Q: Can I use a standard USB cable with my drive?
A: Yes, when a GoFlex drive is mated with a USB 2.0 adapter, you can use a standard USB mini-B cable to connect it to your computer. However, be careful when using longer cables as they may not transfer enough power to allow the drive to function.

Q: Can I use a normal internal drive SATA cables to run my FreeAgent GoFlex drive directly from the computer?
A: This would not be supported since it would require you to leave the drive loose inside the computer or leave the side of the computer open to plug in the power cable, both of which put your equipment at risk.

freeagent-goflex-cable-1USB 2.0 – This cable is the cable that ships in most GoFlex kits since USB 2.0 is still the most popular interface available today. The module and cable can be separated for even more flexibility with standard USB-Mini cables.
freeagent-goflex-cable-2The USB 2.0 cable is detachable allowing easier storage and the ability to use standard USB 2.0 mini-B cables when needed.
freeagent-goflex-cable-3The USB 2.0 cable and Smart module separate from the drive to allow for upgrade to other cables as the need arises.   Additional cartridges (drives) will also be available for purchase if you need higher capacity.
freeagent-goflex-cable-4USB 3.0 – This cable covers the newest version of USB offering much higher transfer rates.  This cable also works with USB 2.0 ports.  The cable does not separate from the Smart module since replacement USB 3.0 cables are not commonly available at this time.
freeagent-goflex-cable-5Firewire 800 – This cable is for users of Mac computers that want extra speed from the drives and have an available Firewire 800 port.
freeagent-goflex-cable-6eSATA – This cable offers higher performance than USB 2.0, but it does require a special eSATA combo port that combines the performance of eSATA and the power supplied by USB 2.0 into a single port.  These types of ports are usually found on newer laptop computers and identified with a symbol that looks like this: esata
freeagent-goflex-cable-7Powered eSATA – Powered eSATA provides high performance like eSATA, but like USB 2.0 it also provides electrical power to operate a drive without needing to use a separate power cable for the drive. This interface is even more rare than eSATA. One of the types of FreeAgent GoFlex upgrade cables, which is compatible with the FreeAgent GoFlex and GoFlex Pro, uses the Powered eSATA interface.
freeagent-goflex-cable-8Thunderbolt – Seagate’s Thunderbolt adapter for GoFlex drives allows any GoFlex, GoFlex Pro, GoFlex Slim, GoFlex Turbo, GoFlex for Mac, GoFlex Slim for Mac, or GoFlex Pro for Mac drive to connect via Apple’s newest interface.

Other cables and accessories available for the GoFlex and GoFlex Pro can be found at the Seagate Online Store under the accessories tab.

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