Hello, I know that memcached is designed to get its speed from the fast access to RAM. But RAM is still very expensive - even with the amount of RAM you get for the same money increasing every year.
When I thought of using PCIe SSDs instead of RAM I wasn't doing this with regard to persistence of objects. I just noticed, that the Fusion- io's ioDrives are working with near-RAM speed, having the PCIe bus as the only bottleneck in speed (don't mix it up with SATA SSDs). An ioDrive 160 GB with SLC memory is available for less than $6,000 and is capable to perform more than 100,000 random IOPS (read and write), whereas with ECC RAM you'd have to pay a multiple of that amount the get the same ressources. I don't know of any way to use a block device (like the ioDrive) as RAM, you can only use RAM as a block device (which doesn't help in this situation). So for the emerging market of PCIe SSDs (many high performance databases are using this as replacement for RAID 10 arrays and large RAM) it would be necessary to extend or branch memcached to support SSD block devices. Did someone start with that, is this possibly already on the roadmap, or did the maintainers refuse to extend memcache with this option for a reason? Btw.: We are using memcached in conjunction with nginx as a web proxy to our backend webservers to cache images and other static files, which improves performance a lot. But 64 GB of RAM is much more expensiv than 160 GB of an ioDrive PCIe SSD. Kind regards Marten
