Disk readahead

It's something you'll probably have to experiment with, though I've only run into issues setting less or no readahead. Readahead assumes long linear reads, such as Vertica does when reading ROS files. What readahead does is continue to fetch from disk into memory cache while returning data to the requestor with the assumption that the next read call will be asking for the next blocks in the same file or stream. I can see this helping on cloud where storage is not direct attached like NVMe, but not sure you want to give up that much instance memory for file caching. So maybe start at 2048 as recommended and keep an eye on iostat and if you start to see significant iowait, then raise the readahead (though that is not the only thing that can cause iowait - also consider premium tier storage, request more IOPS, or NVMe direct attached storage as other options where available to speed up disk I/O)

we are installing vertica on azure and have lvm. https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SupportedPlatforms/VerticaSupportforLVM.htm?zoom_highlight=readahead . Should we change redahead to higher says 8192