Dear all,

Thank you very much for all of the detailed responses. About JVM heap space
recommendation, I am aware that it is possible to optimize 64GB heap space
for JVM, but it may cause lots of pauses in some cases. Anyway, my question
was not about how much memory space is required for Nifi JVM because
definitely it needs lots of effort to optimize JVM for this purpose. In
this question, I was looking for finding different memory use cases in Nifi
architecture. Hence, if I want to summarize the responses about memory use
cases in Nifi I have to say that it is required for JVM on-heap + Disk
caching + off-heap usage for some reference datasets.
Really thanks for all of the responses.

Best regards,
Ali

On Sat, Oct 15, 2016 at 10:43 AM, Joe Witt <joe.w...@gmail.com> wrote:

> The validity of that advice depends on a lot of factors.  G1 changed the
> game a bit for pause times for sure but you can still see larger pause
> times than acceptable for some cases.  In any event I agree that we should
> be more careful with how we describe heap usage.
>
> Thanks
> Joe
>
> On Oct 14, 2016 7:10 PM, "Russell Bateman" <russell.bateman@
> perfectsearchcorp.com> wrote:
>
> Yeah, I spent a bit of time this morning before posting looking for a
> magic 8-10Gb advisory and generally for GC gotchas related to larger heap
> sizes in the 64-bit world, but couldn't find any. We're using 12Gb right
> now for NiFi and haven't noticed any trouble. We vaguely conceive of
> increasing this amount in the future as needed as our servers tend to run
> large amounts of memory.
>
> The statement yesterday on this thread warning against using that much is
> what sent me into Google-it mode. I think this advice is a red herring.
>
> Russ
>
> On 10/14/2016 03:03 PM, Corey Flowers wrote:
>
> We actually use heap sizes from 32 to 64Gb for ours but our volumes and
> graphs are both extremely large. Although I believe the smaller heap sizes
> were a limitation of the garbage collection in Java 7. We also moved to ssd
> drives, which did help through put quite a bit. Our systems were actually
> requesting the creation and removal of file handles faster than traditional
> disks could keep up with (we believe). In addition, unlike with traditional
> drives where we tired to minimize caching, we actually forced more disk
> caching when we moved to ssds. Still waiting to see the results of that on
> our volumes, although it does seemed to have help. Also remember, depending
> on how you code them, individual processors can use system memory outside
> of the heap. So you need to take that into consideration when designing the
> servers.
>
> Sent from my iPhone
>
> On Oct 14, 2016, at 1:36 PM, Joe Witt < <joe.w...@gmail.com>
> joe.w...@gmail.com> wrote:
>
> Russ,
>
> You can definitely find a lot of material on the Internet about Java heap
> sizes, types of garbage collectors, application usage patterns.  By all
> means please do experiment with different sizes appropriate for your case.
> We're not saying NiFi itself has any problem with large heaps.
>
> Thanks
> Joe
>
> On Fri, Oct 14, 2016 at 12:44 PM, Russell Bateman <
> <russell.bate...@perfectsearchcorp.com>russell.bateman@perfectsearch
> corp.com> wrote:
>
>> 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>
>> 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>
>>> 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>
>>>> 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>
>>>>> 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>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
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> A.Nazemian
>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> A.Nazemian
>>>
>>
>>
>>
>> --
>> A.Nazemian
>>
>>
>>
>
>
>


-- 
A.Nazemian

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