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OpenServer 5.0.7 tuning/bdflush/telnet - SCO

Hi, We have OpenServer 5.0.7 It is used as an application server, running a DataFlex-based application, which we access using Telnet. We have about 100 users accessing the system at the same time. We have a new Compaq Proliant ML350G3 P4 2GHz Xeon 1GB RAM Smart Raid 5302 Controller RAID 10, using 4 x 72GB disks. We find that when we access the application, or even connect to the console over telnet/ssh, the screens stop accepting commands for a second or two. The application appears sticky. NBUF = 0 (set by the system). From the docs this equates to 100MB ...

  1. #1

    Default OpenServer 5.0.7 tuning/bdflush/telnet

    Hi,

    We have OpenServer 5.0.7
    It is used as an application server, running a DataFlex-based
    application, which we access using Telnet. We have about 100 users
    accessing the system at the same time.

    We have a new Compaq Proliant ML350G3
    P4 2GHz Xeon
    1GB RAM
    Smart Raid 5302 Controller
    RAID 10, using 4 x 72GB disks.

    We find that when we access the application, or even connect to the
    console over telnet/ssh, the screens stop accepting commands for a
    second or two. The application appears sticky.

    NBUF = 0 (set by the system). From the docs this equates to 100MB
    sar -b shows that cache utilisation is high:
    %rcache = 97
    %wcache = 70 - 95% (varies betwen days)

    sar -r reports freemem = 250000, with no swapping, so we can increase
    NBUF if required.

    According to the Caldera docs, one suggestion is to decrease BDFLUSHR
    and NAUTOUP.

    We changed these to:
    NBFLUSHR = 1
    NAUTOUP = 5

    After reboot we still see this stickiness, although it is hard to
    decide whether it has improved at all.

    Are there any other changes to buffers/kernel parameters that we can
    make to lessen this stickiness.

    The RAID card I think is set to Write-Back, although i need to double
    check this.

    Any advice is appreciated,

    adrian
    adrian Guest

  2. #2

    Default Re: OpenServer 5.0.7 tuning/bdflush/telnet

    In article <58513742.0308131630.59655590posting.google.com >,
    adrian <adrianaot.com.au> wrote:
    >We have OpenServer 5.0.7
    >It is used as an application server, running a DataFlex-based
    >application, which we access using Telnet. We have about 100 users
    >accessing the system at the same time.
    .....
    >We find that when we access the application, or even connect to the
    >console over telnet/ssh, the screens stop accepting commands for a
    >second or two. The application appears sticky.
    How is the performance when you are sitting at the console?
    It may be a telnet/ssh problem or connection problem.

    Bill
    --
    Bill Vermillion - bv wjv . com
    Bill Vermillion Guest

  3. #3

    Default Re: OpenServer 5.0.7 tuning/bdflush/telnet

    [email]bvwjv.comR[/email]EMOVE (Bill Vermillion) wrote in message news:<HJLAL7.Fwxwjv.com>...
    > In article <58513742.0308131630.59655590posting.google.com >,
    > adrian <adrianaot.com.au> wrote:
    >
    > >We have OpenServer 5.0.7
    > >It is used as an application server, running a DataFlex-based
    > >application, which we access using Telnet. We have about 100 users
    > >accessing the system at the same time.
    >
    > ....
    >
    > >We find that when we access the application, or even connect to the
    > >console over telnet/ssh, the screens stop accepting commands for a
    > >second or two. The application appears sticky.
    >
    > How is the performance when you are sitting at the console?
    > It may be a telnet/ssh problem or connection problem.
    >
    > Bill

    Thanks, Bill, for the reply.

    First, I made the changes above on Wednesday morning.
    The "stickiness" continued (ssh and telnet) over two days.
    I had seen this stickiness even doing an "ls" of a directory (via an
    ssh session) with about 30,000 entries.

    Two days later:

    I did not see any stickiness at the console, as you suggested trying.
    However, I did not see the stickiness when performing the "ls"
    mentioned, even over an ssh connection... hmmm.
    Users are not reporting the "stickiness" in their application today,
    either.
    I have made no other changes since my initial tuning of BDFLUSHR two
    days earlier. I don't belive there have been any changes in the use
    of the application by the users. Nor have I made any network
    modifications.

    To say I am confused would be apt. I am going to closely monitor the
    situation over the next few days.

    Sarcheck suggests and increase in NBUF from 130,000 to 156,000;
    however, I think I shall wait before doing that.

    My sar report does indicate that %wcache is consistently a bit low
    (<75%) so I may increase NBUF in a few days.

    cheers,

    adrian
    adrian Guest

  4. #4

    Default Re: OpenServer 5.0.7 tuning/bdflush/telnet

    On 13 Aug 2003 17:30:00 -0700, [email]adrianaot.com.au[/email] (adrian) wrote:
    >We have OpenServer 5.0.7
    >It is used as an application server, running a DataFlex-based
    >application, which we access using Telnet. We have about 100 users
    >accessing the system at the same time.
    (...)
    >After reboot we still see this stickiness, although it is hard to
    >decide whether it has improved at all.
    Are you sure it's the server? Methinks the datacomm might be a
    problem. Try connecting via SSH/telnet through your unspecified
    datacomm link with only one or two users. No way should there be any
    keystroke delays with such a system. Optimizing the system makes
    sense only if the system is heavily loaded or short on resources.
    Yours is more than adequate. Having good performance on the console
    also implies that the box is doing fine.

    If there are still delays with only a few users on the system, it's
    probably the datacomm link. My guess(tm) is that there is a ADSL line
    somewhere in the system. My DSL provider (SBC/PBI/Yahoo/Whatever)
    seems to hate small packets, which are common with telnet and SSH.
    Everything is y and full of delays as something in their system
    waits for more packets to arrive so that it can conglomerate them into
    more efficient larger packets. I see y performance and delays
    using telnet and SSH.

    How are your users connecting to the SCO box?


    --
    Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
    (831)421-6491 pgr (831)336-2558 home
    [url]http://www.LearnByDestroying.com[/url] AE6KS
    [email]jefflcomix.santa-cruz.ca.us[/email] [email]jefflcruzio.com[/email]
    Jeff Liebermann Guest

  5. #5

    Default Re: OpenServer 5.0.7 tuning/bdflush/telnet

    Jeff Liebermann <jefflcomix.santa-cruz.ca.us> wrote in message news:<34prjvgpgu1lbm0aoff2s32k7t9fvqvirp4ax.com>. ..
    > On 13 Aug 2003 17:30:00 -0700, [email]adrianaot.com.au[/email] (adrian) wrote:
    >
    > >We have OpenServer 5.0.7
    > >It is used as an application server, running a DataFlex-based
    > >application, which we access using Telnet. We have about 100 users
    > >accessing the system at the same time.
    > (...)
    > >After reboot we still see this stickiness, although it is hard to
    > >decide whether it has improved at all.
    >
    > Are you sure it's the server? Methinks the datacomm might be a
    > problem. Try connecting via SSH/telnet through your unspecified
    > datacomm link with only one or two users. No way should there be any
    > keystroke delays with such a system. Optimizing the system makes
    > sense only if the system is heavily loaded or short on resources.
    > Yours is more than adequate. Having good performance on the console
    > also implies that the box is doing fine.
    >
    > If there are still delays with only a few users on the system, it's
    > probably the datacomm link. My guess(tm) is that there is a ADSL line
    > somewhere in the system. My DSL provider (SBC/PBI/Yahoo/Whatever)
    > seems to hate small packets, which are common with telnet and SSH.
    > Everything is y and full of delays as something in their system
    > waits for more packets to arrive so that it can conglomerate them into
    > more efficient larger packets. I see y performance and delays
    > using telnet and SSH.
    >
    > How are your users connecting to the SCO box?

    Thanks, Jeff, for the reply.

    Users connect over ethernet (LAN) and telnet.
    Actually, we upgraded the server hardware and software (P2 450/
    OpenServer 5/0/5) on that weekend and after the upgrade we noticed
    this stickiness. This is why I think it is the server that is the
    problem and not a network issue.

    This stickiness was not noticeable when we only had one or two users
    on the system (during testing), again suggesting that tuning was
    required.

    cheers,

    adrian
    adrian Guest

  6. #6

    Default Re: OpenServer 5.0.7 tuning/bdflush/telnet

    adrian wrote:
    > I will try to set a time to make the boot time changes you suggest to
    > NBUF (it is a production server so we have to schedule downtime) and
    > get goo dfeedback from the users. However, I am not sure that the
    > size of the buffer cache is an issue just that the frequncy of
    > flushing the dirty buffers may have been the problem. As mentioned
    > above, we did have NBUF=90000 on our 5.0.5 server and now it is
    > slightly higher, so perhaps the size of NBUF is an issue.
    If the cache is smaller, there will be less room for it to aculate
    dirty buffers. Therefore the pause when it suddenly has to flush a huge
    number of dirty buffers to disk at the same time will be smaller. Of
    course, so will the benefit of the cache for reading. But since the
    buffer cache size is not separately tunable for read vs. write, you must
    balance its effects this way.

    Setting BDFLUSHR to 1 and NAUTOUP to a low value helps to mitigate the
    effects of dirty buffer flushing. So that's another way to balance
    things.
    >Bela<
    Bela Lubkin Guest

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