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Overview articles - Vista ReadyBoost using USB Flash Memory and Hybrid Hard Disk

           1. USB Flash Memory for Windows Vista ReadyBoost

           2. Hybrid Hard Disks and Beyond

          

USB Flash Memory for Windows Vista ReadyBoost
September 20, 2006
 
By  Loyd Case
If you're reading this to see how fast today's USB flash memory keys transfer data, then you should look elsewhere. This isn't about moving large amounts of digital imagery or audio around. This is strictly about ReadyBoost.

What is ReadyBoost?
ReadyBoost is a technology built into Windows Vista that caches disk reads onto a flash memory device. It can work with USB memory keys, flash memory cards, such as SD and CompactFlash, and other types of flash devices. It caches all types of file reads, not just the working set, nor just DLL's or other persistent operating system data.

ReadyBoost does not cache file writes—it's a write-through cache. That way, you never lose any precious data that's meant to be written to a hard drive. After all, a flash memory key can get yanked out of a system at any time. The cache itself is encrypted using AES-128 encryption, so no one can steal your flash memory key and casually browse through the cache file to see what you've been doing. Continued... Microsoft's Tom Archer presented a small FAQ written by Matt Ayers on Archer's blog. What follows is a summary of a few of Matt's comments.

Some people note that reading from flash memory is actually slower than reading from a fast hard drive. As it turns out, this is true mostly for large, sequential file reads. The drive is assisted by 2MB-16MB of onboard data buffer, which is in itself much faster than flash memory. However, ReadyBoost is smart enough to just let the system read large, sequential blocks of data directly from the hard drive.

Where ReadyBoost comes in is with small blocks of random I/O, like paging files, or pulling other random, small amounts of data. Need a DLL or OCX file for a particular app? ReadyBoost can serve it up faster than the disk can locate it. Basically, if the drive head has to move a substantial amount to find small chunks of data, ReadyBoost can improve performance. If a drive is streaming a video or loading a large game level, then ReadyBoost gets out of the way.

The catch when it comes to hardware performance is this caching and serving up of small, random bits of data. As it turns out, many flash memory devices aren't particularly good at this. They are often optimized for moving large chunks of data, but not necessarily good at lots of random accesses of bits of data and applications. Much of this has to do with the tiny controller embedded in every USB memory device. Some are good at small, random access reads and others are not. Another issue is the way flash memory is laid out. Some larger capacity devices that can be had fairly cheaply get their high transfer rates by using a small amount of very fast flash memory, with the bulk being slower memory. In effect, the fast flash is acting as a buffer for the slower flash.

The minimum requirements for a USB memory device to be ReadyBoost capable is 2.5MB/sec for 4K random access reads and 1.5MB/sec for 512K random writes—and that rate has to be achieved across the whole flash memory space. When you plug a USB memory device into the system, Vista actually does a performance check to see if the device meets the standard. Vista won't allow you to use a device it thinks will slow the system down. Note that USB hard drives won't work.

Microsoft's general recommendation for maximum benefit from ReadyBoost is to match the capacity of the flash device to the size of your system's main memory. So if you have 2GB of system RAM, use a 2GB USB key. Note that some benefit is gained from using any flash device, and the capacities supported for ReadyBoost range from 256MB to 4GB.

With these thoughts in mind, let's look at a few memory devices. Continued... We gathered up nine different devices, all 1 GB or larger, from eight different manufacturers. All these USB flash drives are readily available, and all cost under $90 (with 1GB devices typically costing less than $50).

Note that we chose these units pretty much at random. Several (Crucial, Sony, and SanDisk) were supplied by the manufacturer. The rest were either purchased retail or online.

While some of these products are quite plain, others offer unique features. Let's take a brief look at each one.

Apacer Handy Steno HT203
This is one of the larger memory keys. The cap is permanently affixed by a wire. It also comes with a handy docking cradle, so you don't have to hunt around the bottom or back of your PC for a free USB port.

Corsair Flash Readout 2.0GB
The tiny BCD (bistable cholesteric display) readout lets you know exactly how much capacity you have. It's otherwise fairly ordinary.

Crucial Gizmo Overdrive
Crucial ships this speedy, compact little unit that looks quite ordinary.

OCZ Rally2
The OCZ USB stick offers a hard, metallic shell, but is otherwise undistinguished. Continued...

Patriot Xporter
This white model is easy to spot and is also quite cheap.

Patriot Xporter XT
This is the only 4GB unit we tested. The rubberized shell is hard to lose, but is also bulky. It's cost-effective for a 4GB unit, and is fast to boot.

Sandisk Cruzer Titanium
You'll never lose the cap on the Cruzer, but it's the priciest 2GB model we tested. But you get what you pay for.

Sony MicroVault Tiny
Sony accurately calls this USB key "tiny." It's also very, very easy to lose. But small is still pretty cool, and it's not particularly expensive.

Verbatim Store n Go Pro
This blue, 1GB unit looks a bit different, but the actual shell design is pretty standard. The Pro version shown here ships with data encryption software. Continued...

We tested these USB keys on the system we built for Windows Vista. The system has 2GB of system memory and is running Windows Vista RC1 with the latest updates.

Setting up and testing for ReadyBoost is easy. When you first plug a USB memory key into a Vista system, you'll see the following screen:

Click "Speed up my system." Vista will test the USB key's performance, then pop up a property sheet. If the USB flash key is ReadyBoost capable, you'll see a property sheet that asks you if you want to use ReadyBoost. Just check the "Use this device" radio button to enable ReadyBoost. You can also adjust the size of the ReadyBoost cache file.

If Vista's flash memory test fails, then you'll see the property sheet, only this time you're informed that the device isn't fast enough for ReadyBoost. You cannot turn on ReadyBoost if Vista believes your flash key is too slow. After all, why would you want to slow down your system?

 

So which of our nine USB flash memory keys work with ReadyBoost? Drum roll, please.

 

Memory Key Capacity Price ReadyBoost?
 
Apacer Handy Steno HT203 2GB $65 Yes
 
Corsair Flash Readout 2GB $85 No
 
Crucial Gizmo Overdrive 2GB $75 Yes
 
OCZ Rally2 2GB $55 No
 
Patriot Xporter 2GB $38 No
 
Patriot Xporter XT 4GB $85 Yes
 
Sandisk Cruzer Titanium 2GB $85 Yes
 
Sony MicroVault Tiny 1GB $45 Yes
 
Verbatim Store n Go Pro 1GB $49 Yes

Of our nine USB keys, six pass Vista's ReadyBoost test. Three don't. It's not really surprising that the lowball unit—the Patriot Xporter 2GB at $38—doesn't pass. But we were a bit surprised that Corsair's pricey Readout didn't either. The price/performance king is the Patriot Xporter XT, with 4GB of storage for about the same price as some 2GB units.

Read our DVD Burner Roundup.

The most convenient USB key is the Apacer, with its USB docking cradle, while the tiny Sony model and the retractable Sandisk offer their own unique advantages.

Final Thoughts
We make no claims as to how fast these units read and write large volumes of data. But clearly, not all drives work with Vista's ReadyBoost, and we suggest steering away from the low-cost, 2GB models, just as a rule of thumb. But as we've seen, pricey units may not pass Vista's ReadyBoost test, either.

We fully expect other types of USB devices to arrive on the scene, specifically designed for ReadyBoost. But a fast flash memory key can serve double duty, allowing you to transport essential data and speed up Vista.

Copyright (c) 2006 Ziff Davis Media Inc. All Rights Reserved.

 
Hybrid Hard Disks and Beyond
December 14, 2005

By Victor Loh
Last Tuesday, IDEMA hosted a symposium in entitled "HDD Dynamics: Interfaces, Electronics, Architecture, and Reliability". IDEMA, which stands for International Disk Drive Equipment and Materials Association, is a trade association representing 340 companies from the $30 billion disk drive industry. At the event we attended, representatives from Adaptec, Agere Systems, Broadcom, Hitachi GST, Intel, M-Systems, Microsoft, Network Appliance, Samsung, Seagate, and Western Digital were given the opportunity to speak on issues such as emerging interfaces, new electronic designs and integration, sector architecture, and reliability testing.
One of the topics discussed at the symposium dealt with the incorporation of solid-state storage with traditional magnetic disks. Hybrid hard disk drives, as they're called, combine a magnetic hard disk drive and flash memory into a single device. The use of solid state media in consumer and enterprise storage is already widespread: It's in our cameras, MP3 players, USB drives, and mobile phones—and its market share will continue to expand. At the same time, the price of flash memory has been decreasing by about 30% to 50% per year. The areal density of magnetic drives continues to grow as the price per gigabyte falls. With the hybrid HDD, manufacturers seek to combine the robustness, low-power consumption, and speed of flash media with the extraordinary storage density and low cost of magnetic drives. Continued... Microsoft's hybrid hard disk design features a non-volatile (NV) cache added to the hard drive to store frequently used sectors for fast boot and resume times. M-Systems's Director of Technical Marketing, Esther Spanjer, notes that 90% of users, on average, use only 10% of operating system sectors. By duplicating the most commonly used data onto the NV cache, you can minimize dependency on the hard drive for frequently accessed sectors and speed up performance. A cache size of at least 128MB is recommended, but drive manufacturers could conceivably incorporate caches as large as 4GB or more to store critical system data like registry or favorites info. Microsoft's hybrid drive design is currently supported only in Vista, but wider adoption is expected as standardization of the platform expands.

Intel's "Robson" cache takes a different approach, placing the NV cache directly onto the motherboard. With the entire operating system loaded onto flash memory, booting can occur directly from the cache. Once again, a minimum 128MB cache is recommended, but 2GB to 4GB sizes could provide more flexibibility. Continued... What do we get from all this hybrid integration? Lower power consumption, for starters. Disk reads and writes from flash allow the hard disk to stay in a power-saving state with the spindle stopped. Samsung's Dan Barnetson estimates a 9% lower consumption overall. On a laptop, the power savings could add up to an hour of additional battery life.


Faster boot and resume is another advantage. The first 3 to 5 seconds after initially powering up a PC are spent spinning up hard drive platters and synchronizing heads before the boot process can begin. Booting straight from the flash cache eliminates this latency without sacrificing disk performance: Flash can nearly saturate the SATA protocol's 1.6 GB/sec throughput. Working models using Intel's Robson cache have been able to shorten boot time down to less than half a minute. It's the same story for resuming from either shutdown or suspend modes. Critical data is written to the flash cache before your laptop goes to sleep, hibernates, or powers off. Upon resume, it's available instantaneously.

Finally, hybrid storage solutions are more reliable. Mobile applications favor robustness, and flash, as a solid-state medium, boasts superior shock resistance. Also, lower operating duty cycles for your HDDs means less spinning, less heat, longer drive life, and less frequent disk failure. Continued... Three strategies exist for implementing non-volatile memory into hybrid HDDs. The first involves an embedded flash disk. It's an easy, small-footprint solution that incorporates a controller and flash memory onto a single chip. It requires minimal motherboard real estate and provides a NOR interface that works with the existing HDD controller. From a design standpoint, it is much simpler than other options below. It doesn't require completely redesigning existing hard drive architecture. Management software for the flash disk can be supplied by the flash manufacturers.

Also a one-chip solution, using raw NAND flash (the kind found in CompactFlash and USB drives) with existing HDD controllers is cheaper than an embedded flash disk, but it requires additional research and development costs. With the broad array of NAND memory types, cross compatibility is not guaranteed, as many flash chips are not compatible among vendors. The software to manage the NAND memory will also need to be developed.

The third solution uses raw NAND with a dedicated NAND controller. It solves the issue of multi-source flash chips. This two-chip solution requires more PCB space than the embedded flash disks or the NAND disks with HDD controllers. It also has similar drawbacks to the NAND-and-HDD-controller design, including a lack of existing software support and additional development requirements. Continued... Increased hard disk areal density is one of the primary driving forces for the tremendous growth in HDD storage capacity over the past few decades, but we've reached a point where further bit per inch (bpi) and track per inch (tpi) growth is making reliable data retrieval difficult. Areal densities in excess of 150–200 Gbits/inē have made traditional 512-byte sectors inadequate for error-correcting code (ECC).

An IDEMA-sponsored committee found that increasing the standard sector size to 4096 bytes would provide a sufficient platform for future high-areal density drives. This larger 4K standard would allow ECC to maintain the same bit error rate (BER) without sacrificing signal to noise ratio (SNR) . Longer sectors decrease the per-sector overhead among larger swaths of data, and bit space is used more efficiently. With larger 4K sectors, drives will benefit with not only enhanced reliability and tolerance, but greater capacity as well.

The migration from 512B to 4K sectory sizes will require systematic changes that will occur over time. Production of 4K sector drives is expected to start in 2007, but a transition period will follow for a number of years after as the market moves to standardize on the 4K native block size drives. Operating systems like Windows XP, for example, will still need to support 512B emulation for the continued function of legacy drives. Vista, scheduled for release in 2006, will take another 2-3 years before becoming a mainstream OS.

According to Curtis Stevens of Western Digital, support for both 512B and 4K native sector drives in the meantime may incur some performance penalties. Mapping 512B logical sectors to larger physical sectors, for example, may require a read-modify-write (RMW) process if a host writes data to a logical block address (LBA) that is out of alignment with the physical sector boundaries. While there may be no measurable penalties for read operations or write operations that begin and end on physical sector boundaries, writes that start or end in the middle of a physical sector may suffer a slowdown. Writes within a track, for instance, may require an additional revolution. Two revolutions may be required for writes that span an entire track.

Click here for more Storage articles on ExtremeTech.

Another issue brought up by the transition has to do with block alignment. Windows 3.1 through XP normally format on odd sector boundaries, while other operating systems format on even sector boundaries. To function optimally, alignment requirements will need to be reported so that newer systems can format legacy device data accordingly. File system formats and virtual memory will also need tweaks to ensure misalignment doesn't occur. Adaptations to host software, drivers, and firmware will be needed to prepare for the transition.



Copyright (c) 2006 Ziff Davis Media Inc. All Rights Reserved.