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Fwd: [cfarm-admins] Extremely Slow Disk Access On GCC119

Hello list, has anyone experienced problems on the AIX POWER8 system?

---------- Forwarded message ----------
From: R0b0t1 <>
Date: Sun, Sep 10, 2017 at 9:58 AM
Subject: Re: [cfarm-admins] Extremely Slow Disk Access On GCC119
To: David Edelsohn <>

Do you care to explain? I'm not trying to tell you how to do your job,
I'm trying to make you aware of a problem.

I do not understand how this could only be a problem with the disk
controller, because I have never encountered such poor performance. If
it is only a problem with the disk, has the disk been failing this
whole time?

I hope you do not mind, but I will be forwarding this to the GCC
mailing list. I am concerned by your replies.

On Sun, Sep 10, 2017 at 3:47 AM, David Edelsohn <> wrote:
> You're analysis is completely wrong.
> David
> On Sep 10, 2017 10:08 AM, "R0b0t1" <> wrote:
>> Thank you for the response!
>> I don't necessarily mean to request funding for the AIX system in this
>> ticket but I feel like I should point out that the system is more or
>> less unusable if something requires any IO. Assuming the HD is
>> anything modern it seems to me this is a scheduling or caching issue
>> in the AIX kernel.
>> To reiterate, something that should take a few minutes took a day due
>> to slow IO. Something that should have taken a fraction of a second
>> was taking minutes.
>> That it could possibly be the AIX kernel makes me want to ask if it
>> would be possible to migrate the system to Linux. However, I would
>> assume someone needs it for doing testing on AIX. I can also just as
>> well use GCC112.
>> I am doing my best to not to monopolize GCC119, but it is very hard to
>> design around certain IO operations being very slow. I am not sure if
>> this is impacting any users; it doesn't seem like the AIX system
>> receives regular use.
>> Cheers,
>>      R0b0t1
>> On Sun, Sep 10, 2017 at 1:45 AM, David Edelsohn <> wrote:
>> > The backing disk array for the virtual I/O disks was under-designed
>> > for the configuration of the system.  There is a request to upgrade
>> > the disk controller, but unclear if that will be funded.  The I/O
>> > system already has been tuned with bigger buffers so the performance
>> > is much better than it was when originally installed.
>> >
>> > Please remember that all of the systems are shared systems and if
>> > there is some limitations to the system, it affects all users, so
>> > please try not to monopolize or overload the systems.
>> >
>> > Thanks, David
>> >
>> > On Sun, Sep 10, 2017 at 8:18 AM, R0b0t1 via cfarm-admins
>> > <> wrote:
>> >> Hello,
>> >>
>> >> I apologize for creating another ticket. I am in the process of
>> >> running rm on a directory structure which is very quickly removed on
>> >> the Linux CF machines I have used the command on.
>> >>
>> >> In addition the setup of a few software packages took about a day in
>> >> total due to disk access when running configure scripts. On Linux,
>> >> this completes in a matter of minutes.
>> >>
>> >> Is this a problem with AIX/jfs?
>> >>
>> >> Respectfully,
>> >>      R0b0t1
>> >> _______________________________________________
>> >> cfarm-admins mailing list
>> >>
>> >>

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