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I use windows server 2008r2 with role Hyper-V. The guest system is Ubuntu 12.04 LTC (64 bit). It is situated on the dynamic virtual hard disk /dev/sda.
There is postgresql-9.1 (amd64) on the Ubuntu 12.04. There is the database (the database size is 400 GB) on the /dev/sdb
hdparm shows: IO=150MB/s
On the picture you can see that "postgresql" uses 97% of IO, but it is only 5 MB/s. But hdparm shows that IO for /dev/sdb is 150 MB/s
How can I use hard disk on 100%? Detail you can see in the question https://serverfault.com/questions/558852/postgresql-9-1-amd64-configuration-only-for-database-search-400gb-database
Wild guess: you're using a magnetic hard drive (not SSD) and most time is spent on seeking the drive. Without knowing how your DB structure is set up (including indexes) and what your query is, it's difficult to say. – nitro2k01 – 2013-12-04T13:07:58.610
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My question is: IO is 150 MB/s. On the picture you can see 4 processes "postgresql". One of this processes uses only 5 MB/s (97%). I think it is problem. How can I change postgresql.conf, that this process will use 100 MB/s? Is it real? – AmShegar – 2013-12-04T13:21:32.727
Moreover, there are another 5 virtual machines on this disk. They are running. Is it important for IO? all vitual machines and vhd disks are situated on one disk. – AmShegar – 2013-12-04T13:25:49.730