AStalUK Share Posted March 16, 2016 (edited) I have a fresh install of CentOS7 (x64) setup within HyperV (Server 2008 R2), I've allocated it a 80GB HDD and 8GB RAM. I've also installed PostgreSQL 9.5 for use with my db (currently it's running on Server 2008 R2/PostgreSQL 9.0), which I am now looking to tweak the performance for. So the first thing I am looking to tweak is the amount of shared memory available to the db by allocating 4GB to Shared Memory (shmmax), but if I run ipcs -lm I get; ------ Shared Memory Limits -------- max number of segments = 4096 max seg size (kbytes) = 18014398509465599 max total shared memory (kbytes) = 18014398442373116 min seg size (bytes) = 1 This would seem to indicate I have a far larger swap file than should be possible. Does anyone know why this is occurring, is it a bug within my VM setup (I'm seeing it in other CentOS VM's I have setup)? Given the above should I skip doing anything with shmmax and move on to adjusting other settings within PostgreSQL.conf and carry on testing with pgbench? Thanks. *note* I would consider myself a novice with Linux, I know some command line and a little around it's workings but it's still very much a learning process for me at the moment. Really starting to see how much of a sheltered life I've lived running Windows Servers. Link to post Share on other sites
Unobscured Vision Share Posted March 16, 2016 Get your config sorted first, then deal with the VM settings. Hyper-V has always been really fussy in my experience, though; so I'm not really a good one to specifically answer why it isn't changing the limit for you. Link to post Share on other sites
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