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  • 1.  hdisk0 is very busy after I modify some parameters

    Posted Fri June 29, 2007 03:20 PM

    Originally posted by: SystemAdmin


    System p550 2 PCU (partition into 4) AIX 5.3L, memory 3790 M, with BAAN 5c on hdisk2 and Oracle 10g on hdisk1 (data on hdisk3)
    Last night, I modified three parameters maxuproc (sys0)= 512, maxservers (aio0) =300 and and lgpg_regions = 119 (16M), based on SGA of Oracle.

    However, as the busy hour, the topas indicated that the hdisk0, which is all of OS programs staged, is always 95% busy, and there seem to have high % of read (Kb-read) and write (K-write). On the hand did not indicated busy CPU% by any user. Some high number of PageIn and Pageout.

    I have another set of AIX test box with very similar set up (same hw, same parameter setups, same programs setup). but testing the BAAN/Oracle did not show very busy on hdisk0.

    So how can I solve the problem? very urgent! Please help.

    #AIX-Forum


  • 2.  Re: hdisk0 is very busy after I modify some parameters

    Posted Fri June 29, 2007 03:52 PM

    Originally posted by: VirtualGreg


    There is some oracle user setup you need to do - sounds like you are doing lots of paging. See http://www-03.ibm.com/servers/enable/site/peducation/wp/9a46/9a46.pdf for details.
    #AIX-Forum


  • 3.  Re: hdisk0 is very busy after I modify some parameters

    Posted Fri June 29, 2007 04:45 PM

    Originally posted by: SystemAdmin


    I got that paper before. I have used some of the info to set up the parameter for lgpg_regions, but I did not set the lock_sga to TRUE, because I have secondary application -BAAN, that needs the memory. However the same settings on my second AIX box did not have the paging problem. As I checked both systems, I found that the only difference between tow are the different set-up the paging space. On this one, only one paging space as default /dev/hd6, with size of 1.5 times of totoal memory; while on the other system, I configured into two paging space (same 1.5 times of memory) with equal size.

    However, I doubt it is the paging space problem (not because I mentioned in last post). How can I ensure that it is caused by paging space?

    If it is, how can I modify the paging space, ie add another one ( I know how to do this) and shrink the old one (little risk for me)?
    #AIX-Forum


  • 4.  Re: hdisk0 is very busy after I modify some parameters

    Posted Fri June 29, 2007 04:51 PM

    Originally posted by: VirtualGreg


    the way you describe your problem - sounds like you are doing lots of paging. filemon will tell you what's churning away, vmstat will show you your paging I/O rates. I haven't set up the large page support before - my guess was perhaps you missed something and your large pages aren't being used, hence after the change you are paging a lot more because you ran out of 4k pages??? Just a guess...
    #AIX-Forum


  • 5.  Re: hdisk0 is very busy after I modify some parameters

    Posted Fri June 29, 2007 08:02 PM

    Originally posted by: SystemAdmin


    Well, i added another paging space, half size of my hd6, then activated the lock_sga=true, enter proper sga size values (shar, buffer, large,java), then test a select run in the oracle. One case, the hdisk0 was still 10% busy, page out high again.
    #AIX-Forum


  • 6.  Re: hdisk0 is very busy after I modify some parameters

    Posted Sun July 01, 2007 10:51 PM

    Originally posted by: SystemAdmin


    I add another paging00 of 3200 M on hdisk1. Someone in the Oracle field gave me other suggestions for SGA. I will try it on MOndy. Another OS parameter, maxuproc, although I increased it to 512 for Oracle 10g R2, it did not seem working. I wonder how high it can be? Check on the internet, User with Oracle uses above 500. Some users with DB2 even increased to 4096. How is this value calculated? I have not found anyone explain its detail except its meaning.
    #AIX-Forum


  • 7.  Re: hdisk0 is very busy after I modify some parameters

    Posted Mon July 02, 2007 11:53 AM

    Originally posted by: SystemAdmin


    If you are using jfs2 file systems and haven't already considered it, take a look at implementing CIO (concurrent i/o) for the oracle data file systems. Oracle manages paging. If you arent' using CIO, every call is paged to the OS (paging space) and to the database, in essence double paging. We had a similar experience and CIO was a huge help. However please note, if this is a data warehouse or there are a large number of sequential reads, CIO may not be the best option for your environment. There are a couple of other parms that need to change when implementing CIO but all the information can be found in this whitepaper: http://www-03.ibm.com/servers/enable/site/peducation/wp/9a46/9a46.pdf

    Hope this helps,
    Sherry
    #AIX-Forum


  • 8.  Re: hdisk0 is very busy after I modify some parameters

    Posted Tue July 03, 2007 09:53 PM

    Originally posted by: SystemAdmin


    According to many other papers about the large page features of POWER-5 system, They also talked about the maxperm%, maxclient% and minperm% (default 80, 80, 20, viewed by ioo -a). I have not configures three parameters because I am not sure whether those numbers are related to the large page features. Do they set up as a whole?

    Those changes were supposedly to benefit my Oracle 10g and Baan. But I noticed that under topas and filemon, busy paging even when Oracle and baan run very low, 0~1%.

    Also another tuning paper for AIX 5.3 specifies whole set of ioo -a, vmo -a, Because there are so many tuning parameters, How do I verify those parameters in order to implement? ie. one parameter a time or some other methods.
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  • 9.  Re: hdisk0 is very busy after I modify some parameters

    Posted Fri July 20, 2007 05:40 PM

    Originally posted by: vbaranov


    Try this:

    maxuproc=2048

    lru_file_repage=0
    maxperm%=90
    minperm%=5
    maxclient%=90
    strict_maxperm=0
    strict_maxclient=0

    Also, while it's not directly connected to this particular issue, try
    maxpout=513
    minpout=256
    in order to increase system's responsiveness if some programs generate the very large amounts of output.

    All of these attributes are dynamic. See http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.prftungd/doc/prftungd/disk_io_pacing.htm
    #AIX-Forum