Ali,

"not recommended to dedicate more than 8-10 GM to JVM heap space" by whom? Do you have links/references establishing this? I couldn't find anyone saying this or why.


Russ

On 10/13/2016 05:47 PM, Ali Nazemian wrote:
Hi,

I have another question regarding the hardware recommendation. As far as I found out, Nifi uses on-heap memory currently, and it will not try to load the whole object in memory. From the garbage collection perspective, it is not recommended to dedicate more than 8-10 GB to JVM heap space. In this case, may I say spending money on system memory is useless? Probably 16 GB per each system is enough according to this architecture. Unless some architecture changes appear in the future to use off-heap memory as well. However, I found some articles about best practices, and in terms of memory recommendation it does not make sense. Would you please clarify this part for me?
Thank you very much.

Best regards,
Ali


On Thu, Oct 13, 2016 at 11:38 PM, Ali Nazemian <alinazem...@gmail.com <mailto:alinazem...@gmail.com>> wrote:

    Thank you very much.
    I would be more than happy to provide some benchmark results after
    the implementation.
    Sincerely yours,
    Ali

    On Thu, Oct 13, 2016 at 11:32 PM, Joe Witt <joe.w...@gmail.com
    <mailto:joe.w...@gmail.com>> wrote:

        Ali,

        I agree with your assumption.  It would be great to test that
        out and provide some numbers but intuitively I agree.

        I could envision certain scatter/gather data flows that could
        challenge that sequential access assumption but honestly with
        how awesome disk caching is in Linux these days in think
        practically speaking this is the right way to think about it.

        Thanks
        Joe

        On Thu, Oct 13, 2016 at 8:29 AM, Ali Nazemian
        <alinazem...@gmail.com <mailto:alinazem...@gmail.com>> wrote:

            Dear Joe,

            Thank you very much. That was a really great explanation.
            I investigated the Nifi architecture, and it seems that
            most of the read/write operations for flow file repo and
            provenance repo are random. However, for content repo most
            of the read/write operations are sequential. Let's say
            cost does not matter. In this case, even choosing SSD for
            content repo can not provide huge performance gain instead
            of HDD. Am I right? Hence, it would be better to spend
            content repo SSD money on network infrastructure.

            Best regards,
            Ali

            On Thu, Oct 13, 2016 at 10:22 PM, Joe Witt
            <joe.w...@gmail.com <mailto:joe.w...@gmail.com>> wrote:

                Ali,

You have a lot of nice resources to work with there. I'd recommend the series of RAID-1 configuration
                personally provided you keep in mind this means you
                can only lose a single disk for any one partition.  As
                long as they're being monitored and would be quickly
                replaced this in practice works well.  If there could
                be lapses in monitoring or time to replace then it is
                perhaps safer to go with more redundancy or an
                alternative RAID type.

                I'd say do the OS, app installs w/user and audit db
stuff, application logs on one physical RAID volume. Have a dedicated physical volume for the flow file
                repository.  It will not be able to use all the space
                but it certainly could benefit from having no other
                contention.  This could be a great thing to have SSDs
                for actually.  And for the remaining volumes split
                them up for content and provenance as you have. You
                get to make the overall performance versus retention
                decision. Frankly, you have a great system to work
                with and I suspect you're going to see excellent
                results anyway.

                Conservatively speaking expect say 50MB/s of
                throughput per volume in the content repository so if
                you end up with 8 of them could achieve upwards of
                400MB/s sustained. You'll also then want to make sure
                you have a good 10G based network setup as well.  Or,
                you could dial back on the speed tradeoff and simply
                increase retention or disk loss tolerance.  Lots of
                ways to play the game.

                There are no published SSD vs HDD performance
                benchmarks that I am aware of though this is a good
                idea.  Having a hybrid of SSDs and HDDs could offer a
                really solid performance/retention/cost tradeoff.  For
                example having SSDs for the
                OS/logs/provenance/flowfile with HDDs for the content
                - that would be quite nice.  At that rate to take full
                advantage of the system you'd need to have very strong
                network infrastructure between NiFi and any systems it
                is interfacing with  and your flows would need to be
                well tuned for GC/memory efficiency.

                Thanks
                Joe

                On Thu, Oct 13, 2016 at 2:50 AM, Ali Nazemian
                <alinazem...@gmail.com <mailto:alinazem...@gmail.com>>
                wrote:

                    Dear Nifi Users/ developers,
                    Hi,

                    I was wondering is there any benchmark about the
                    question that is it better to dedicate disk
                    control to Nifi or using RAID for this purpose?
                    For example, which of these scenarios is
                    recommended from the performance point of view?
                    Scenario 1:
                    24 disk in total
                    2 disk- raid 1 for OS and fileflow repo
                    2 disk- raid 1 for provenance repo1
                    2 disk- raid 1 for provenance repo2
                    2 disk- raid 1 for content repo1
                    2 disk- raid 1 for content repo2
                    2 disk- raid 1 for content repo3
                    2 disk- raid 1 for content repo4
                    2 disk- raid 1 for content repo5
                    2 disk- raid 1 for content repo6
                    2 disk- raid 1 for content repo7
                    2 disk- raid 1 for content repo8
                    2 disk- raid 1 for content repo9


                    Scenario 2:
                    24 disk in total
                    2 disk- raid 1 for OS and fileflow repo
                    4 disk- raid 10 for provenance repo1
                    18 disk- raid 10 for content repo1

                    Moreover, is there any benchmark for SSD vs HDD
                    performance for Nifi?
                    Thank you very much.

                    Best regards,
                    Ali





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