Hard Drive versis Flash Drive

A hard drive is more durable in the long run.

Also, a flash drive will run much hotter. The flash is quieter though.

Being mechanical design doesn't mean it's more prone to the failure. Over 20 years of owning various computers, I have had one hard disk failure but more than half dozen memory failures. Solid state drives do not have moving part, but don't make an incorrect assumption of solid state being more durable. Agreed on the heat, power consumption and noise.

Have also had a half dozen memory failures. Unfortunately, none had to do with flash or hard drives!

Anecdotal evidence about hard drive reliability varies widely. Some people, like Jylee, almost never have a failure, while many people receive hard drives which are doa or fail within the first days, weeks, or months. The user comments on specific hard drives which are posted at NewEgg.com are good illustrations of this unpredictability, even within the same model. Besides random or age-related failure modes, deficient manufacturing processes and quality control, and sometimes bug-laden firmware design clearly play a part in many drive problems.

I think that the best example I have ever encountered of Mark Twain's famous dictum that "there are lies, damned lies, and statistics," is the hard drive mtbf (mean time between failure) specification. Essentially what the manufacturers do (and these numbers are very approximate, chosen just to illustrate the point), is to operate 100 hard drives for a year, find that one has failed, and declare that the mtbf is 100 years. Of course, had all 100 been operated for even say 20 years, nearly all of them would most likely have failed due to accumulated mechanical wear and tear.

In my own fairly extensive experience, with about 7 or 8 computers over 10 years or so, containing around 25 or so internal and external hard drives, drive life has averaged around 3 years. A few months in some cases, many years in other cases. FWIW, I've had best results with Western Digital.

I back up important data files to BOTH a second internal hard drive and an external hard drive. I update those backups daily, and once a month or so I create a drive image of my system partition, so that if it fails or is corrupted I don't have to spend a lot of time reinstalling all the software. I consider all of those practices to be fundamental to any serious use of a computer, although remarkably few people do those kinds of things.

Flash memory, whether on a flash card or in one of the new solid state hard drives, has a fundamental limitation in how many erase/write cycles it can undergo before failing. Here is a quote from this Wikipedia writeup on solid state hard drives:

Limited write (erase) cycles: Flash-memory cells will often wear out after 1,000 to 10,000 write cycles for MLC, and up to 100,000 write cycles for SLC[18], while high endurance cells may have an endurance of 1–5 million write cycles (many log files, file allocation tables, and other commonly used parts of the file system exceed this over the lifetime of a computer).[33][34][35] Special file systems or firmware designs can mitigate this problem by spreading writes over the entire device (so-called wear leveling), rather than rewriting files in place.[36] In 2008 wear leveling was just beginning to be incorporated into consumer level devices.[18] However, effective write cycles can be much less, because when a write request is made to a particular memory block, all data in the block is overwritten even when only part of the memory is altered. The write amplification, as referred by Intel, can be reduced using write memory buffer.[37] In combination with wear leveling, over-provisioning SSD flash drives with spared memory capacity also delays the loss of user-accessible memory capacity. NAND memory can be negatively impacted by read and program (write) disturbs arising from over accessing a particular NAND location. This overuse of NAND locations causes bits within the NAND block to erroneously change values. Wear leveling, by redirecting SSD writes to lesser-used NAND locations, thus reduces the potential for program or write disturbs.[38] An example for the lifetime of SSD is explained in detail in this wiki.[dubious – discuss] SSDs based on DRAM, however, do not suffer from this problem.

As a result of wear leveling and write combining, the performance of SSDs degrades with use [39][40]. Eventually, wear leveling will use each page on the drive at least once, so further writes always involve a block erase. Although write combining (if supported by the device) offers advantages, it causes internal fragmentation in the SSD which degrades the sequential read speed. Such fragmentation cannot be mitigated by the operating system.

As you can gather from this, the reliability degradation of flash memory based on the limitated number of erase/write cycles can be minimized by having an amount of storage capacity which is as far in excess of the amount of data being stored as possible.

I believe that the forthcoming Windows 7, now available in release candidate form, is the only Windows os which is optimized for ssd's with respect to these and other considerations. Although that is of greatest significance to system drive applications, not to drives used mainly for long-term storage of data files.

Regards,
-- Al