Tom Lane wrote:
"Joshua D. Drake" <jd@xxxxxxxxxxxxxxxxx> writes:
Jeff Trout <threshar@xxxxxxxxxxxxxxxxxxxxxx> wrote:
in this case it was 24hrs of data - about 1500 wal segments. During
this time the machine was nearly complete idle and there wasn't very
much IO going on (few megs/sec).
Exactly. Which is the point I am making. Five minutes of transactions
is nothing (speaking generally).. In short, if we are in recovery, and
we are not saturated the I/O and at least a single CPU, there is a huge
amount of optimization *somewhere* to be done.
You sure about that? I tested CVS HEAD just now, by setting the
checkpoint_ parameters really high,
Well I haven't tested CVS HEAD yet, but on 8.2:
avg-cpu: %user %nice %sys %iowait %idle
0.12 0.00 0.30 12.22 87.35
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 172.26 2927.74 46.31 14668 232
sda1 182.63 2927.74 46.31 14668 232
sdb 1.40 0.00 41.52 0 208
sdb1 10.38 0.00 41.52 0 208
sdb2 0.00 0.00 0.00 0 0
sdc 96.21 946.11 14.37 4740 72
sdc1 99.20 946.11 14.37 4740 72
sdd 0.00 0.00 0.00 0 0
sdd1 0.00 0.00 0.00 0 0
And:
2007-12-13 00:55:20 EST LOG: restored log file "00000001000007E10000006B" from archive
2007-12-13 00:55:34 EST LOG: restored log file "00000001000007E10000006C" from archive
2007-12-13 00:55:48 EST LOG: restored log file "00000001000007E10000006D" from archive
2007-12-13 00:56:01 EST LOG: restored log file "00000001000007E10000006E" from archive
2007-12-13 00:56:14 EST LOG: restored log file "00000001000007E10000006F" from archive
2007-12-13 00:56:28 EST LOG: restored log file "00000001000007E100000070" from archive
2007-12-13 00:56:42 EST LOG: restored log file "00000001000007E100000071" from archive
This is a 14 Spindles in RAID 10 on sda and sdc. As a correlation, exact
same hardware (and OS) and off peak production load of 2.25 million
xacts per hour (at data point), 3million per hour at peak.:
avg-cpu: %user %nice %sys %iowait %idle
23.30 0.00 15.28 33.07 28.35
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 2078.80 23693.60 10628.00 118468 53140
sda1 4139.80 23693.60 10628.00 118468 53140
sdb 24.00 94.40 318.40 472 1592
sdb1 87.40 94.40 318.40 472 1592
sdc 694.00 22207.20 4113.60 111036 20568
sdc1 1575.00 22207.20 4113.60 111036 20568
sdd 826.80 3.20 8691.20 16 43456
sdd1 828.60 3.20 8691.20 16 43456
I would expect that recovery would be faster than prod. Maybe I am off
my rocker but the warm standby isn't doing anything but restoring the logs.
This is going to be hard to test with 8.3 with this data set but I will
see if I can get some other numbers with 8.3.
Sincerely,
Joshua D. Drake
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