Another Flash SSD myth -- faster boot times.
IDC is selling thier recent technical report and benchmark results comparing Flash SSD to spinning disk for $10,000.00 to vendors and investment analysts. Of course they are not publishing the results openly (gotta buy the report), but for those who have been watching the stock market you may have seen a number of Flash SSD stocks downgraded since IDC's report came out.
Now, although we don't have details on IDC's benchmark, journalists have characterized the results as showing a much smaller performance improvement over spinning disk than what the Flash SSD hypesters have been claiming -- and that IDC also found a number of areas where they were surprised to see HDD outperform SSD.
Well, last week IDC offered a 10% discount as a contest prize for guessing the correct answer to a question based on the benchmark results. I played the game, results below.
-----Original Message-----
From: Zina Ashkouri [mailto:ZAshkouri@idc.com]
Sent: Monday, August 25, 2008 8:28 AM
To: anon_reader@anon.com
Subject: Guess which drive boots the fastest and get a 10% discount!
Thank you for accepting IDC's challenge to guess which PC drive technology is the fastest!
a) 1st generation hybrid HDD
b) 4,200rpm traditional HDD
c) MLC SSD
d) 2nd Generation hybrid HDD
e) 7,200rpm traditional HDD
f) SLC SSD
You guessed right, the correct answer is e!
http://www.idc.com/getdoc.jsp?containerId=213285
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Now, the question you are all probably asking is WHY?
The answer is that, like MOST I/O intensive applications-in-the-REAL-world, an OS boot procedure must complete a large number of read requests that cannot even be issued by the host to the drive until a previous write command has completed and has been acknowledged back to the application (in this case, the OS). This is known as the "synchronous" I/O bottleneck. So...(a) the NAND Flash "read/write" penalty slows the whole device down whenever the workload is a mix of read and write (synchronous or not), and (b) the presence of synchronous I/O in the workload further degrades performance down to the speed of small-block writes.
And, for those who know how NAND flash works...you know that this problem will be getting worse with increasing NAND Flash bit density and not better.
That's why IDC found that system boot times were faster with 7,200RPM disk than with any of the Flash SSD's they tested.
Of course, when the SSD hypesters tout "faster boot time", they don't tell you they are comparing to a 4,200 RPM disk.
Another Flash SSD myth bites the dust!!!
Now, Intel's X25-E (the super-expensive SLC version) has a massive DRAM write-cache to try to help with slow writes. It will be interesting to see if this much-ballyhooed new Flash SSD entry with 20x more DRAM than a laptop disk will boot as fast as a 7,200 RPM disk...knowing a little about Intel I'm quite convinced that Intel would not have allowed their new SSDs to be tested.