On Thu, Sep 4, 2008 at 1:24 PM, Ulrich <ulrich.mierendorff@xxxxxxx> wrote: > Hi, > I have a virtual server with 256 MB of RAM. I am using it as a webserver, > mailserver and for postgres. So there is something like 150MB left for > postgres. > > Here are my configs (I haven't benchmarked...) > max_connections = 12 (I think, I will not have more parallel connections, > because I only have 10 PHP worker threads) > shared_buffers = 24MB > work_mem = 1MB > maintenance_work_mem = 16MB > > (effective_cache_size = 80MB) > > Normally, the file-cache is part of the free ram. But on my virtual server, > it looks like if there is one big file cache for the whole hardware node and > I do not have my own reserved cached, so it is not easy to find a good value > for effective_cache_size. > > I've also benchmarked the file-cache using dd (100MB file) > > 1. Read from HDD: > 104857600 bytes (105 MB) copied, 8.38522 seconds, 12.5 MB/s > 2. Read from Cache: > 104857600 bytes (105 MB) copied, 3.48694 seconds, 30.1 MB/s > > That is really really slow (10 times slower than on my other machine). > > What would you do now? Increasing shared_buffers to 100MB and setting > effective_cache_size to 0MB? Or increasing effective_cache_size, too? Stop using a virtual server? I wouldn't set shared_buffers that high just because things like vacuum and sorts need memory too. > > Thanks for help. > > Regards, > -Ulrich > > -- > Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
