On Sun, Apr 17, 2011 at 10:59 AM, Phoenix <phoenix.kiula@xxxxxxxxx> wrote: > TOP does not show much beyond "postmaster". How should I use TOP and > what info can I give you? This is what it looks like: We're basically looking to see if the postmaster process doing the vacuuming or reindexing is stuck in a D state, which means it's waiting on IO. hot the c key while it's running and you should get a little more info on which processes are what. > 4799 postgres 15 0 532m 94m 93m D 0.7 1.2 0:00.14 > postmaster That is likely the postmaster that is waiting on IO. > VMSTAT 10 shows this: > > r b swpd free buff cache si so bi bo in cs us sy id wa > 3 14 99552 17900 41108 7201712 0 0 42 11 0 0 8 34 41 16 > 2 17 99552 16468 41628 7203012 0 0 1326 84 1437 154810 7 66 12 15 > 3 7 99476 16796 41056 7198976 0 0 1398 96 1453 156211 7 66 21 6 > 3 17 99476 17228 39132 7177240 0 0 1325 68 1529 156111 8 65 16 11 So, we're at 11 to 15% io wait. I'm gonna guess you have 8 cores / threads in your CPUs, and 1/8th ot 100% is 12% so looks like you're probably IO bound here. iostat tells us more: > The results of "iostat -xd 10" is: > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s > avgrq-sz avgqu-sz await svctm %util > sda 0.00 7.41 0.30 3.50 2.40 87.29 1.20 43.64 > 23.58 0.13 32.92 10.03 3.81 > sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 > 0.00 0.00 0.00 0.00 0.00 > sdc 0.00 18.32 158.26 4.10 2519.32 180.98 1259.66 > 90.49 16.63 13.04 79.91 6.17 100.11 100% IO utilization, so yea, it's likely that your sdc drive is your bottleneck. Given our little data is actually moving through the sdc drive, it's not very fast. > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s > 8GB memory in total. 1GB devoted to PGSQL during these operations. > Otherwise, my settings are as follows (and yes I did make the vacuum > settings more aggressive based on your email, which has had no > apparent impact) -- Yeah, as it gets more aggressive it can use more of your IO bandwidth. Since you > What else can I share? That's a lot of help. I'm assuming you're running software or motherboard fake-raid on this RAID-1 set? I'd suggest buying a $500 or so battery backed caching RAID controller first, the improvements in performance are huge with such a card. You might wanna try testing the current RAID-1 set with bonnie++ to get an idea of how fast it is. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
