Other than virtual memory, How about RAM usage for Varnish?
Is it much RAM needed?
Best Answer
You can run Varnish in a few different modes. One uses the disk as the cache repository and in this mode, you can safely restart Varnish without losing your cache. This also means you can support a very large cache and let the OS's IO cache keep the most requested content in the server's memory. This mode is configured with the flag -s file,/var/lib/varnish/varnish_storage.bin,1G
The other mode is memory-only - Varnish keeps all cached data only in memory, never writing to disk. This can deliver extremely fast response times, but the cache size is limited to how much memory your server has. Also, if you restart Varnish you lose the cache and suddenly requests will start flooding your backend. Note, however, that Varnish is extremely stable and we only ever restart Varnish when an update is released (every 6 months or so). This mode is configured like -s malloc,3200M
So to answer your question, Varnish performs much better with more RAM. We have a Amazon EC2 instance with 3.5GB RAM and no swap and give Varnish 3GB of RAM for caching. Currently we have almost the entire backend site in cache, including images and PDF files etc. I can definitely recommend this setup.
Use the malloc method. It will try to put everything in RAM and the kernel will swap it out if needed. This way you are using memory and disk together.
At the same time file performs much better than malloc when you start hitting disk. For more info, see:
Best Answer
You can run Varnish in a few different modes. One uses the disk as the cache repository and in this mode, you can safely restart Varnish without losing your cache. This also means you can support a very large cache and let the OS's IO cache keep the most requested content in the server's memory. This mode is configured with the flag
-s file,/var/lib/varnish/varnish_storage.bin,1GThe other mode is memory-only - Varnish keeps all cached data only in memory, never writing to disk. This can deliver extremely fast response times, but the cache size is limited to how much memory your server has. Also, if you restart Varnish you lose the cache and suddenly requests will start flooding your backend. Note, however, that Varnish is extremely stable and we only ever restart Varnish when an update is released (every 6 months or so). This mode is configured like
-s malloc,3200MSo to answer your question, Varnish performs much better with more RAM. We have a Amazon EC2 instance with 3.5GB RAM and no swap and give Varnish 3GB of RAM for caching. Currently we have almost the entire backend site in cache, including images and PDF files etc. I can definitely recommend this setup.