IDS Forum

KAIO Question

Posted By: John
Date: Thursday, 29 March 2007, at 5:44 p.m.

To any AIX / IDS gurus out there,

Background:

We are running IDS 10.00 FC4 on AIX 5.2 TL8. We have been having some AIO issues with two boxes (each is a 390 with 8 cpu's), one dev and one prod. We tuned the DEV box with min and max AIX AIO 5, and 180 respectively, and it is running fine, and seemingly wide open. There are actually over 360 IO threads running, but only a dozen or so showing that they are clocking any CPU time. This machine, with (all cpu and aio) noage activated, is seemingly screaming along.
PROD is set with min max 1 and 180 respectively (the machine notes show that it should be set to MIN =1) and it only has one thread running, and it does not even show it clocking any CPU. Although on the database side there are 140 aio vp's (threads), it appears that something is holding AIX from spawning any more (Unix)AIO processes, and it is seemingly creating a bottleneck. This database also has noage activated on all cpu and aio vp's, but the machine seems to not be spawning off any of the seemingly needed (Unix)AIO procs. The tech does not want to increase the prod config based on the machine notes.
The boxes, prod and dev, have 8 and 128, and 4 and 128 cpu and aio vp's configured, respectively, again, all noage. Dev is a shared box and only has 4 cpuvp's.
Tech has showed that although I/O should be in the 80mb per second, we are using but a small fraction of that.

Questions:
A. Does setting the AIX MIN aio value to 1 disable the spawning of additional threads/processes as needed?, and does setting it at say "5" and bouncing the machine enable and open it up to AIO thread volume increases as AIX deems appropriate? According to the aforementioned scenario, it certainly appears to, but if I could get an explanation of exactly why/how it works...???

B. On AIX, in regards to the PSE driver, the machine notes for AIX 5.2 and 5.3 say it should be loaded via "/usr/bin/strload" (generic configuration) and that it works hand in hand with enabling KAIO. Is there a preferred way as a DBA to ensure that it is activated on both of our servers and configured properly? I have read all the documentation I can find, but it does not answer these specific questions. Does the NETTYPE have to reflect socstr in order to work?

C. We have been advised through documentation available on the IBM website that we should enable KAIO, but have been unable to get it to come on/with the cooked files, even when building the DB in raw, and have been unable to find the necessary settings to config to get it to activate.

I have requested to turn KAIO on for this server. They have cooked filesystems, and yes, I would alwys use KAIO with raw, but there has been documentation that shows that you can still use it with KAIO enabled and get almost raw performance.

Here is an excerpt from the onconfig file. You can see we have discontinued using processor affinity until we can get the I/O issue resolved, and scaled the aiovp's way back. We have reduced the number of aiovps until we can get the ones that are present to work. This is a data warehouse database with several fragmented tables, of about 700GB in size.

.....
SERVERNUM 1 # Unique id corresponding to a OnLine instance
DBSERVERNAME nmprdbdev_shm # Name of default database server
DBSERVERALIASES nmprdbdev_tcp,nmprdbdev_tcp2 # List of alternate dbservernames
SINGLE_CPU_VP 0 # Set to 1 if VPCLASS cpu, num=1
MULTIPROCESSOR 1 # Set to 1 if VPCLASS cpu, num>1

#VPCLASS cpu,num=4,aff=4-7,noage # Number of cpu virtual processors (vps)
#VPCLASS aio,num=8,aff=0-7,noage # Number of IO vps

VPCLASS cpu,num=8 # Number of cpu virtual processors (vps)
VPCLASS aio,num=8 # Number of IO vps (at least 1 per XPSdbspace

NETTYPE ipcshm,1,250,CPU # Poll thread type,no. of cpu's,max users,class
NETTYPE soctcp,4,250,NET # Poll thread type,no. of cpu's,max users,class
......

Thanks,

John

Messages In This Thread

• KAIO Question
  John -- Thursday, 29 March 2007, at 5:44 p.m.
  • Re: KAIO Question
    ART KAGEL, BLOOMBERG/ 731 LEXIN -- Thursday, 29 March 2007, at 5:54 p.m.
    • Re: KAIO Question
      John -- Friday, 30 March 2007, at 8:53 a.m.
      • Re: KAIO Question
        ART KAGEL, BLOOMBERG/ 731 LEXIN -- Friday, 30 March 2007, at 8:56 a.m.
        • Re: KAIO Question
          John -- Friday, 30 March 2007, at 9:17 a.m.
          • Re: KAIO Question
            ART KAGEL, BLOOMBERG/ 731 LEXIN -- Friday, 30 March 2007, at 9:27 a.m.
            • RE: KAIO Question
              Robert Roussey\(IT\) -- Friday, 30 March 2007, at 12:28 p.m.
  • Re: KAIO Question
    ART KAGEL, BLOOMBERG/ 731 LEXIN -- Thursday, 29 March 2007, at 5:58 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.