Micron releases half-terabyte laptop SSDs

Re:Micron releases half-terabyte laptop SSDs by hyuen on Wednesday January 05, 2011 @02:09AM (#2070231)

While SSDs are wonderful for random reads, writes are still very expensive due to their large erase blocks. In a small write (typical OLTP workload), the entire block has to be rewritten --typically 128kB-- even if the modified data is much smaller. That's why it is very important to make the application aware of this fact, or use a log-structured filesystem on top of it.

I believe that for most web applications the ratio is 80% reads, 20% writes, that's why no one has noticed this behavior.

Another even more concerning issue is the wear-out, SSD cells can't take more than ~10000 rewrites. While there is firmware taking care of invalidating those blocks, eventually we can expect data loss if not backed up properly.

I think SSDs are great, as long as we understand their limits... For my laptop I have one and I love it, but I would be seriously doubtful about the safety of my information in some database using purely SSDs.

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Re:Micron releases half-terabyte laptop SSDs by pmjordan on Wednesday January 05, 2011 @06:32AM (#2070674)

For servers, you'd typically choose SLC Flash rather than the cheaper MLC. The memory cells survive about an order of magnitude more flash cycles and are also slightly faster. Also, I hope you're not assuming that your data is safe on the only component with critical moving parts in a modern computer...

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