On Mon, Dec 8, 2008 at 10:17 AM, Rafael Domiciano <rafael.domiciano@xxxxxxxxx> wrote: > Here's the output. While the process was running my database get sometime > without doing anything. > You said that I probably get low numbers, but what numbers? We're looking for MB/s and the bi/bo fields in bmstat (blocks in / blocks out) > [root@postgres banco]# time dd if=/dev/zero of=/banco/testfile bs=1000000 > count=500 > 500+0 records in > 500+0 records out > 500000000 bytes (500 MB) copied, 85,4485 seconds, 5,9 MB/s > real 1m25.451s > user 0m0.003s > sys 0m1.617s > [root@postgres banco]# time dd of=/dev/null if=/banco/testfile > 976562+1 records in > 976562+1 records out > 500000000 bytes (500 MB) copied, 47,5025 seconds, 10,5 MB/s > real 0m47.543s > user 0m0.457s > sys 0m1.470s > And the vmstat output: > > procs -----------memory---------- ---swap-- -----io---- --system-- > -----cpu------ > r b swpd free buff cache si so bi bo in cs us sy id > wa st > 0 8 111760 56432 19812 1305692 0 0 744 832 2488 1518 5 3 46 > 46 0 Here, the bi/bo numbers are 768 in and 832 out. That's k/second we're looking at. Lots of the same numbers cut out. > procs -----------memory---------- ---swap-- -----io---- --system-- > -----cpu------ > r b swpd free buff cache si so bi bo in cs us sy id > wa st > 0 6 111760 55452 18528 1296412 0 0 88 25040 1843 1436 2 3 34 > 61 0 > 1 7 111760 52352 18540 1296472 0 0 36 15220 1467 944 3 2 27 > 68 0 > 0 6 111760 54152 18552 1296568 0 0 88 42296 1609 822 1 2 38 > 59 0 > 1 8 111760 52412 18580 1296752 0 0 172 27052 1567 950 2 3 27 > 69 0 > 0 6 111724 53904 18632 1297008 320 0 580 1504 1902 2320 5 6 23 > 66 0 > 1 6 111724 54280 18660 1297200 4 0 200 1060 2014 1783 5 3 44 > 48 0 > 1 7 111676 51388 16340 1302348 8 0 156 1212 1684 848 2 2 53 > 42 0 > 1 6 111668 55040 14864 1301048 0 4 152 46328 1595 5108 1 5 40 > 54 0 Now we're showing that we can write to the disk at 25 to 42 Megs a second, not too bad. But it looks really bursty, like it can sustain this throughput for only a few seconds. Try writing a larger file and run vmstat 10 or 60 as well and see what the average over a longer time with a larger file is. I get a feeling your machine has a hard time sustaining throughput for some reason. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
