Performance problem when copying data on rx2620 - HP UX

This is a discussion on Performance problem when copying data on rx2620 - HP UX ; Hello, i have strange problems on one of my systems: I run a HP rx2620 with HP-UX 11iv2, two CPU's, 2GB RAM. I want to copy roundabout 2GB of data (many small files) from the connected RAID to a NAS ...

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Thread: Performance problem when copying data on rx2620

  1. Performance problem when copying data on rx2620

    Hello,
    i have strange problems on one of my systems:
    I run a HP rx2620 with HP-UX 11iv2, two CPU's, 2GB RAM. I want to copy
    roundabout 2GB of data (many small files) from the connected RAID to a
    NAS that is connected via nfs. After i started the copy command, the cp
    process takes more and more of the cpu, until the systems gets so slow,
    that the users cannot work withit anymore. Even after i stopped the cp
    process, the systems remains slow. It has a CIFS sever running, and the
    smbd processes take a lot of cpu after the copy action, until i reboot
    the server.
    The same happens, if i use tar instead of cp, so i guess, the problem
    is some kernel parameter or similar, not the cp process itself.
    Does anyone has an idea what the problem could be?
    Every help is welcome.

    Christoph


  2. Re: Performance problem when copying data on rx2620

    azzurro1971 wrote:
    > i have strange problems on one of my systems:
    > I run a HP rx2620 with HP-UX 11iv2, two CPU's, 2GB RAM. I want to copy
    > roundabout 2GB of data (many small files) from the connected RAID to a
    > NAS that is connected via nfs. After i started the copy command, the cp
    > process takes more and more of the cpu, until the systems gets so slow,
    > that the users cannot work withit anymore. Even after i stopped the cp
    > process, the systems remains slow. It has a CIFS sever running, and the
    > smbd processes take a lot of cpu after the copy action, until i reboot
    > the server.
    > The same happens, if i use tar instead of cp, so i guess, the problem
    > is some kernel parameter or similar, not the cp process itself.
    > Does anyone has an idea what the problem could be?
    > Every help is welcome.


    One thing to consider is running Caliper and seeing where all the CPU
    time goes.

    Does the system remain slow if you unmount the NAS filesystem and
    remount it?

    rick jones
    --
    a wide gulf separates "what if" from "if only"
    these opinions are mine, all mine; HP might not want them anyway...
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

  3. Re: Performance problem when copying data on rx2620

    Perhaps your dbc_max_pct kernel tunable is higher than you want.
    The copy operation could be moving a lot of data into the file
    system buffer cache. That could cause more CPU time in the
    smbd processes as they need to search through more buffer cache
    entries to see if they can find data that they reading and
    writing.

    --
    - [HP is committed to respecting your privacy.] For more information,
    visit http://welcome.hp.com/country/us/en/...e_privacy.html
    - or contact me at: [mike.stroyan@hp.com or
    HP Privacy Mailbox , 20555 SH 249, MS 040307 , Houston, Texas 77070]

    Mike Stroyan, mike.stroyan@hp.com

  4. Re: Performance problem when copying data on rx2620

    On 2 Sep 2005 10:16:06 -0700, "azzurro1971"
    wrote:

    >Hello,
    >i have strange problems on one of my systems:
    >I run a HP rx2620 with HP-UX 11iv2, two CPU's, 2GB RAM. I want to copy
    >roundabout 2GB of data (many small files) from the connected RAID to a
    >NAS that is connected via nfs. After i started the copy command, the cp
    >process takes more and more of the cpu, until the systems gets so slow,
    >that the users cannot work withit anymore. Even after i stopped the cp
    >process, the systems remains slow. It has a CIFS sever running, and the
    >smbd processes take a lot of cpu after the copy action, until i reboot
    >the server.
    >The same happens, if i use tar instead of cp, so i guess, the problem
    >is some kernel parameter or similar, not the cp process itself.
    >Does anyone has an idea what the problem could be?
    >Every help is welcome.


    The probable reason the system remains slow after the cp is killed is
    that the file buffer cache is already filled with I/Os and it is taking
    a while for the buffers to flush. I've seen an apparent performance
    difference of 10:1 between a cp and cp;sync;sync.

  5. Re: Performance problem when copying data on rx2620

    On Fri, 02 Sep 2005 10:16:06 -0700, azzurro1971 wrote:

    > Hello,
    > i have strange problems on one of my systems:
    > I run a HP rx2620 with HP-UX 11iv2, two CPU's, 2GB RAM. I want to copy
    > roundabout 2GB of data (many small files) from the connected RAID to a
    > NAS that is connected via nfs. After i started the copy command, the cp
    > process takes more and more of the cpu, until the systems gets so slow,
    > that the users cannot work withit anymore. Even after i stopped the cp
    > process, the systems remains slow. It has a CIFS sever running, and the
    > smbd processes take a lot of cpu after the copy action, until i reboot
    > the server.
    > The same happens, if i use tar instead of cp, so i guess, the problem
    > is some kernel parameter or similar, not the cp process itself.
    > Does anyone has an idea what the problem could be?
    > Every help is welcome.
    >



    I'd recommend a copy of Dave Olker's "Optimizing NFS Performance" for a
    starter. My main guess is buffer cache is at defaults which will kill
    performance.

    Chris

    --
    Chris "Saundo" Saunderson saundo@earthlink.net
    Unix/CCNA/CCDA Guy Powered by Linux and the Orb.


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