NAND Flash Better Than DRAM For PC Performance 205
Lucas123 writes "Adding NAND flash memory to a PC does more for performance than DRAM and costs less, according to a new study. As the price difference between the two memory types widens, NAND flash will become the memory of choice in the PC. The effects of NAND flash adoption are already being felt in the DRAM market, as revenue in 2011 is expected to decline 11.8%."
A bit confusing (Score:4, Insightful)
I think all they mean is that dram isn't really all that cost effective as a data cache. For data that one intends to export out the network. Storing that data on a SSD, assuming it's a relatively static data set (which most is), uses far less power and costs less than purchasing an equivalent amount of DRAM (and the much larger mobo required to hold that DRAM). The access times are plenty fast enough to still saturate the network. That's all. Not rocket science.
This has been known for several years. Replicate a small server with 8-16G of ram + a 160G SSD + a 2TB HDD sits right on the sweet spot. In fact, even 4G of ram would probably be fine. The idea is not to replace your hard drive but instead to insert another layer of cheap caching to avoid having to maintain a complex, expensive, power hungry HDD storage system just to get better throughput.
-Matt
Re:One Problem (Score:5, Insightful)
I work with flash daily, we make products that last 15 years with flash. Without large failure rates. The problem is not with flash. It's with the SSD implementation. It's the "let's replace harddisks with flash! and don't change anything else!" that causes problems. Because of this normal filesystems are used, that assume to be on spinning harddrives, which have no issue in writing the same sector twice, or just writing 1 sector at once. On flash on the other hand you need to do wear-leveling, and have large erase blocks. Both are handled on the SSD right now, and that's where it fucks up. It needs to maintain an internal mapping of all the flash, accounting for wear-level and shifting blocks around. One error in this internal management and your disk is junk. Even with your fancy journaling filesystem (ntfs/ext3,4/...) you are just 1 power failure away from losing your data.
Compact flash cards, SD cards, SSD, USB sticks all see this problem. So far we've only found a few suppliers of Compact flash cards which guarantee the internal management is safe, and we tested it and found it to be true. SD cards, I've a few broken "industrial grade" SD cards on my desk as proof that this is not the case. SSD is to large for our product, so I have no tests for these, but I expect the problem to be the same.
We use raw flash, with linux and JFFS2 or UBIFS. Which is a filesystem designed to run on flash, raw flash. Wake me when "SSD" offers that solution.
(TRIM is not a sollution, it's a workaround)