SSD vs Memory – The End is Nigh!
Check out this performance analysis of the recent Mtron 16G drives…
Here are some key things to take away:
* You can fully saturate the drive with 4k reads and still get 100MBps throughput.
* The disk can STILL do 80MB/s write throughput
* It’s cheap – $400
So, if you were to buy a new server, would you rather spend $1500 on 16G of memory or or 60G of SSD?
Think about it. With ~4 SSDs you can get about 400MB/s sequential reads.
Even if you’re on a 4 core system the CPU is going to have a HARD time keeping up with whatever task you want to do.
You’re no longer seek bound.
So why do you even need memory any more?
Just buy 4-8 core machines with 2G of ram and put the rest of the cash into SSD.
Granted, there are some applications with HUGE data requirements. Say you need a 1T database. Would you rather buffer it with 16G of memory or 60G of SSD?
At 400MB/s I’m willing to bet the SSD benchmarks would look pretty solid.
How would you accomplish this though? Mount the SSDs as swap :)
Update: One problem here. The SSD could only be used as a disk device which means that Linux buffers and the page cache can’t use the device so DBs that rely on filesystem caching would really suffer (though innodb would work just fine).
Maybe the next step is to KEEP these as ram devices to begin with.