Re: HELP: Informix Online on HP-K460 is NOT-SCALABLE?
My 0.02c worth on this.
If one process has a page from the database in shared memory and they
update it or otherwise cause it to lock then if another process wants
to access that page it has to wait for the page to be free. As the
page is in a buffer already and does not need to be read from disk the
process will wait for that buffer. So in some cases high lock
contention will also increase buff waits. It does not always mean that
there are insufficient buffers.
Also other shared memory structures for sysmaster etc are in buffers.
In some cases a process will need to wait for one of those buffers
also.
HTH
Jason
On 6 Oct 1997 03:08:07 GMT, "James Francis" <jfrancis@dxi.com> wrote:
>Thanks for responding...
>SaTriGuy <satriguy@aol.com> wrote in article
><19971004200101.QAA06456@ladder02.news.aol.com>...
>> >Online on HP-K460 is NOT-SCALABLE?
>> >From: "James Francis" <jfrancis@dxi.com>
>> >Date: Sat, Oct 4, 1997 13:48
>>
>> First of all, your buffers are really way too small for this type of
>machine,
>> unless this is a data-warehouse system and you are planning on doing
>> everything via PDQ.
>>
>Most of my testing was with BUFFERS set at 148000. I set them back there
>now,
>still no change
>>
>> What is the case number? I'd like to see onstat -p, onstat -g seg, the
>output
>> of several "select * from sysmaster:syssqexplain order by sqx_estcost
>desc",
>> and the onconfig in the case notes. Can you ensure that this
>information is
>> in the case?
>>
>I'll post the case number tomorrow...
>Here is a copy of an onstat -p. This snap shot was taken after about 1
>hour of running. The bufwaits seem
>high to me but I can't figure out how to bring it down.
>
>INFORMIX-OnLine Version 7.23.UC1 -- On-Line -- Up 01:24:43 -- 810752
>Kbytes
>
>Profile
>dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached
>234164 291355 155797563 99.85 12263 69423 459217 97.33
>
>isamtot open start read write rewrite delete commit
>rollbk
>142933483 3039772 13830362 82826263 195156 0 0 0 0
>
>ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes
>0 0 0 10100.18 990.63 3 6
>
>bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans
>582340 0 22299077 0 0 2 158 1880
>
>ixda-RA idx-RA da-RA RA-pgsused lchwaits
>151713 15148 4062 165252 655377
>
>Here is the onstat -g seq.
>INFORMIX-OnLine Version 7.23.UC1 -- On-Line -- Up 01:27:10 -- 810752
>Kbytes
>
>Segment Summary:
> (resident segments are locked)
>id key addr size ovhd class blkused blkfree
>5125 1381451778 80000000 460800000 7636 V 6313 49937
>6148 1381451777 c0872000 369410048 6516 R 45087 7
>5126 1381451779 d68be000 1654784 632 M 196 6
>Total: - - 831864832 - - 51596 49950
>
>> What is the case number? I'd like to see onstat -p, onstat -g seg, the
>output
>> of several "select * from sysmaster:syssqexplain order by sqx_estcost
>desc",
>> and the onconfig in the case notes. Can you ensure that this
>information is
>> in the case?
>Excellent suggestion on using the select from sysmaster. I will do this
>and add it
>to the case. I basically gave Informix a copy of the Onconfig and output
>from onstat -g act,
>onstat -g rea.>>
>> Madison Pruet
>>
Jason Harris
Informix DBA
Westpac Banking Corporation
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