Thursday, May 31, 2007

Flash Drive vs. External Hard Drive



Why does everyone keep saying flash is faster? Don't get me wrong, I love the benefits of flash, but what's with this crazy rumor? I was curious about this, and other than having direct random access speed, flash is shockingly slow! If you typically transfer files or install software from your flash drive, it isn't faster to use at all. Just look at it's mere 17MB/s transfer rate above! It's like a devilishy fast skinny dude running to grab water from a well, but can't carry it back!

Just recently, external hard drives introduced eSATA capability (with transfer rates of up to 300MB/s!). BUT, from what I've read, all the external hard drive "tests" out there show a max transfer rate of around 70-80MB/s. And burst rate speeds? Forget about'em. Sustained transfer rates and random access times are the only figures to look for. It seems that burst rate figures have negligible impact on overall performance, but I guess the big fat eSATA pipeline isn't going to complete waste with rare burst rates of around 250MB/s. Still sad though...

The good news is Samsung's new "32GB [augmented hybrid hard drive] of NAND [which] reads 300 percent faster (53MB/s) and writes 150 percent quicker (28MB/s)"*** is on it's way to the U.S. soon! Which means a major performance increase in our current USB flash drives to follow as well!


If you're wondering what the heck burst rate is:

"...Burst Rate is Windows dressing to a large extent. The two figures that matter are seek time and STR. Seek time is how fast your librarian can run and STR is how many books per day you can borrow from the library. Burst Rate is how many books you can steal from the library and bring back without getting noticed!"*

Intel:
"Sustained vs. Burst Transfer Rates
Sustained transfers refer to a continued transfer that does not occur from the drive cache. Burst rates refer to data transferred directly to/from the high speed cache. A true indicator of performance is sustained rate; however, most drives are advertised with their faster burst rate.

A typical ATA/100 hard drive bursts at about 100MB/sec from the cache, but has a sustained rate of about 26-42MB/sec, depending on the drive. If you consider a best-case scenario with the 2MB cache full of data, 100MB/sec will quickly deplete the cache and commence transferring at the lower sustained rate.

ATA/66 hard drives are typically less expensive and do not saturate the 66MB/sec bandwidth available. In fact, a hard drive with a sustained transfer rate of 26MB/sec will not even saturate available ATA/33 bandwidth.

In summary, sustained transfer rates should be considered over burst transfer rates for maximum hard drive performance. "*

Flash Pro's:
Quiet operation
Low power consumption
Ultra portability

External HD Pro's:
Blazing speed
Massive storage capacity
Jaw-dropping prices (Seagate Free Agent 750GB for $199, limited offer at Best Buy)

*http://www.hyperossystems.co.uk/07042003/HD4tests.htm
**http://www.intel.com/support/graphics/sb/cs-010481.htm
***http://www.engadget.com/2006/05/23/samsungs-q30-ssd-with-32gb-flash-drive-on-sale-in-june/

If you're wondering, CD-ROM (48x-52x) read speed is around 7-8MB/s.

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