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> 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> 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>
>> 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
>

Reply via email to