Re: AIX 5.2 ML04 jfs2 cio slow and hangs

Holger.VanKoll_at_SWISSCOM.COM
Date: 01/04/05

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    Date:         Tue, 4 Jan 2005 12:58:51 +0100
To: aix-l@Princeton.EDU

    cio does not use filecache - that works as designed
    this is why you increase sga-caching to the amount of memory that uses filecache when there is no cio
     
    iŽd recommend lsof to check cio-usage. mount just tells you, cio will me used by default. cio is not enforced, neither is dio.
     
    also, some filemon-stats when the system is slow would help
     

    ________________________________

    From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of Mark Lamport
    Sent: Monday, January 03, 2005 6:51 PM
    To: aix-l@Princeton.EDU
    Subject: Re: AIX 5.2 ML04 jfs2 cio slow and hangs

    I have filesystemIO_options = setall
    mount command shows if cio is mounted also and it isn't right now.
    I increased db_cache_size from 1G to 4G.
    What other init.ora parameters should I adjust?
    Yes, I am running the 64bit kernel;

    # ls -al /unix

    lrwxrwxrwx 1 root system 21 Nov 13 2003 /unix -> /usr/lib/boot/unix_64

     
    Note, users are saying system running ok on jfs2 when cio not ineffect and really bad when it is and like I said, it appears AIX filesystem cache is not being used as currently nmon shows 10G of 16G free.
     
     
    thanks.
     
    Mark Lamport

            ----- Original Message -----
            From: Holger.VanKoll@SWISSCOM.COM
            Newsgroups: bit.listserv.aix-l
            To: aix-l@Princeton.EDU
            Sent: Monday, January 03, 2005 11:20 AM
            Subject: Re: AIX 5.2 ML04 jfs2 cio slow and hangs

            and your dba switched from async to setall ?
             
            use
            lsof +fg /you/ora/filesystem to see if cio is really used (flag 0x80)
             

    ________________________________

            From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of Mark Lamport
            Sent: Monday, January 03, 2005 5:57 PM
            To: aix-l@Princeton.EDU
            Subject: AIX 5.2 ML04 jfs2 cio slow and hangs
            
            
            Last week I rebuilt our Oracle 9.2.0.4 production database moving from large file enabled jfs to jfs2 and mounting with the cio flag. The imports ran faster and rman backups ran faster but this morning when the users started hitting the server it slowed down to a crawl. So I unmounted the filesystems and mounted with rw and now the users say the performance is ok. Does anyone have an idea why the concurrent IO is slower when it is suppose to be faster? It also looks like jfs2 is not using AIX filesystem cache, I thought it was suppose to unless the jfs2 filesystem was mounted with the -dio or -cio flag.
            BTW, I had a problem with the system hanging when a rman backup bombed, the fix was APARS IY59082 and IY62591.
             
            thanks.
             
            Mark Lamport
            Sr. PeopleSoft Database Administrator
            Metropolitan Community Colleges
            3200 Broadway Ave.
            Kansas City, Missouri
            64111
             
            816 759-1192
            mark.lamport@kcmetro.edu
             

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