[gpfsug-discuss] Tuning AFM for high throughput/high IO over _really_ long
Jake Carroll
jake.carroll at uq.edu.au
Wed Nov 9 18:27:50 GMT 2016
Scott,
Nar, very much pure AFM to AFM here, hence we are a little surprised. Last time we did this over a longish link we almost caused an outage with the ease at which we attained throughput - but maybe there are some magic tolerances we are hitting in latency and in flight IO semantics that SS/GPFS/AFM is not well tweaked for (yet...)...
Yes - we are catching up at SC. I think it's all been arranged? We are also talking to one of your resources about this AFM throughput behaviour this afternoon. John I believe his name is?
Anyway - if you've got any ideas, am all ears!
>
>
> Today's Topics:
>
> 1. Re: Tuning AFM for high throughput/high IO over _really_ long
> distances (Scott Fadden)
> 2. Re: Tuning AFM for high throughput/high IO over _really_ long
> distances (Jan-Frode Myklebust) (Jake Carroll)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 9 Nov 2016 10:08:42 -0800
> From: "Scott Fadden" <sfadden at us.ibm.com>
> To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> Subject: Re: [gpfsug-discuss] Tuning AFM for high throughput/high IO
> over _really_ long distances
> Message-ID:
> <OF438B4E0A.3DF65F65-ON88258066.006179EA-88258066.0063ABE4 at notes.na.collabserv.com>
>
> Content-Type: text/plain; charset="utf-8"
>
> Jake,
>
> If AFM is using NFS it is all about NFS tuning. The copy from one side to
> the other is basically just a client writing to an NFS mount. Thee are a
> few things you can look at:
> 1. NFS Transfer size (Make is 1MiB, I think that is the max)
> 2. TCP Tuning for large window size. This is discussed on Tuning active
> file management home communications in the docs. On this page you will
> find some discussion on increasing gateway threads, and other things
> similar that may help as well.
>
> We can discuss further as I understand we will be meeting at SC16.
>
> Scott Fadden
> Spectrum Scale - Technical Marketing
> Phone: (503) 880-5833
> sfadden at us.ibm.com
> http://www.ibm.com/systems/storage/spectrum/scale
>
>
>
> From: Jake Carroll <jake.carroll at uq.edu.au>
> To: "gpfsug-discuss at spectrumscale.org"
> <gpfsug-discuss at spectrumscale.org>
> Date: 11/09/2016 09:39 AM
> Subject: [gpfsug-discuss] Tuning AFM for high throughput/high IO
> over _really_ long distances
> Sent by: gpfsug-discuss-bounces at spectrumscale.org
>
>
>
> Hi.
>
> I?ve got an GPFS to GPFS AFM cache/home (IW) relationship set up over a
> really long distance. About 180ms of latency between the two clusters and
> around 13,000km of optical path. Fortunately for me, I?ve actually got
> near theoretical maximum IO over the NIC?s between the clusters and I?m
> iPerf?ing at around 8.90 to 9.2Gbit/sec over a 10GbE circuit. All MTU9000
> all the way through.
>
> Anyway ? I?m finding my AFM traffic to be dragging its feet and I don?t
> really understand why that might be. I?ve verified the links and
> transports ability as I said above with iPerf, and CERN?s FDT to near
> 10Gbit/sec.
>
> I also verified the clusters on both sides in terms of disk IO and they
> both seem easily capable in IOZone and IOR tests of multiple GB/sec of
> throughput.
>
> So ? my questions:
>
> 1. Are there very specific tunings AFM needs for high latency/long
> distance IO?
> 2. Are there very specific NIC/TCP-stack tunings (beyond the type of
> thing we already have in place) that benefits AFM over really long
> distances and high latency?
> 3. We are seeing on the ?cache? side really lazy/sticky ?ls ?als? in
> the home mount. It sometimes takes 20 to 30 seconds before the command
> line will report back with a long listing of files. Any ideas why it?d
> take that long to get a response from ?home?.
>
> We?ve got our TCP stack setup fairly aggressively, on all hosts that
> participate in these two clusters.
>
> ethtool -C enp2s0f0 adaptive-rx off
> ifconfig enp2s0f0 txqueuelen 10000
> sysctl -w net.core.rmem_max=536870912
> sysctl -w net.core.wmem_max=536870912
> sysctl -w net.ipv4.tcp_rmem="4096 87380 268435456"
> sysctl -w net.ipv4.tcp_wmem="4096 65536 268435456"
> sysctl -w net.core.netdev_max_backlog=250000
> sysctl -w net.ipv4.tcp_congestion_control=htcp
> sysctl -w net.ipv4.tcp_mtu_probing=1
>
> I modified a couple of small things on the AFM ?cache? side to see if it?d
> make a difference such as:
>
> mmchconfig afmNumWriteThreads=4
> mmchconfig afmNumReadThreads=4
>
> But no difference so far.
>
> Thoughts would be appreciated. I?ve done this before over much shorter
> distances (30Km) and I?ve flattened a 10GbE wire without really
> tuning?anything. Are my large in-flight-packets
> numbers/long-time-to-acknowledgement semantics going to hurt here? I
> really thought AFM might be well designed for exactly this kind of work at
> long distance *and* high throughput ? so I must be missing something!
>
> -jc
>
>
> _______________________________________________
> gpfsug-discuss mailing list
> gpfsug-discuss at spectrumscale.org
> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>
>
>
>
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> ------------------------------
>
> Message: 2
> Date: Wed, 9 Nov 2016 18:09:14 +0000
> From: Jake Carroll <jake.carroll at uq.edu.au>
> To: "gpfsug-discuss at spectrumscale.org"
> <gpfsug-discuss at spectrumscale.org>
> Subject: Re: [gpfsug-discuss] Tuning AFM for high throughput/high IO
> over _really_ long distances (Jan-Frode Myklebust)
> Message-ID: <5D327C63-84EC-4F59-86E7-158308E91013 at uq.edu.au>
> Content-Type: text/plain; charset="utf-8"
>
> Hi jf?
>
>
>>> Mostly curious, don't have experience in such environments, but ... Is this
> AFM over NFS or NSD protocol? Might be interesting to try the other option
> -- and also check how nsdperf performs over such distance/latency.
>
> As it turns out, it seems, very few people do.
>
> I will test nsdperf over it and see how it performs. And yes, it is AFM ? AFM. No NFS involved here!
>
> -jc
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 9 Nov 2016 17:39:05 +0000
> From: Jake Carroll <jake.carroll at uq.edu.au>
> To: "gpfsug-discuss at spectrumscale.org"
> <gpfsug-discuss at spectrumscale.org>
> Subject: [gpfsug-discuss] Tuning AFM for high throughput/high IO over
> _really_ long distances
> Message-ID: <83652C3D-0802-4CC2-B636-9FAA31EF5AF0 at uq.edu.au>
> Content-Type: text/plain; charset="utf-8"
>
> Hi.
>
> I?ve got an GPFS to GPFS AFM cache/home (IW) relationship set up over a really long distance. About 180ms of latency between the two clusters and around 13,000km of optical path. Fortunately for me, I?ve actually got near theoretical maximum IO over the NIC?s between the clusters and I?m iPerf?ing at around 8.90 to 9.2Gbit/sec over a 10GbE circuit. All MTU9000 all the way through.
>
> Anyway ? I?m finding my AFM traffic to be dragging its feet and I don?t really understand why that might be. I?ve verified the links and transports ability as I said above with iPerf, and CERN?s FDT to near 10Gbit/sec.
>
> I also verified the clusters on both sides in terms of disk IO and they both seem easily capable in IOZone and IOR tests of multiple GB/sec of throughput.
>
> So ? my questions:
>
>
> 1. Are there very specific tunings AFM needs for high latency/long distance IO?
>
> 2. Are there very specific NIC/TCP-stack tunings (beyond the type of thing we already have in place) that benefits AFM over really long distances and high latency?
>
> 3. We are seeing on the ?cache? side really lazy/sticky ?ls ?als? in the home mount. It sometimes takes 20 to 30 seconds before the command line will report back with a long listing of files. Any ideas why it?d take that long to get a response from ?home?.
>
> We?ve got our TCP stack setup fairly aggressively, on all hosts that participate in these two clusters.
>
> ethtool -C enp2s0f0 adaptive-rx off
> ifconfig enp2s0f0 txqueuelen 10000
> sysctl -w net.core.rmem_max=536870912
> sysctl -w net.core.wmem_max=536870912
> sysctl -w net.ipv4.tcp_rmem="4096 87380 268435456"
> sysctl -w net.ipv4.tcp_wmem="4096 65536 268435456"
> sysctl -w net.core.netdev_max_backlog=250000
> sysctl -w net.ipv4.tcp_congestion_control=htcp
> sysctl -w net.ipv4.tcp_mtu_probing=1
>
> I modified a couple of small things on the AFM ?cache? side to see if it?d make a difference such as:
>
> mmchconfig afmNumWriteThreads=4
> mmchconfig afmNumReadThreads=4
>
> But no difference so far.
>
> Thoughts would be appreciated. I?ve done this before over much shorter distances (30Km) and I?ve flattened a 10GbE wire without really tuning?anything. Are my large in-flight-packets numbers/long-time-to-acknowledgement semantics going to hurt here? I really thought AFM might be well designed for exactly this kind of work at long distance *and* high throughput ? so I must be missing something!
>
> -jc
>
>
>
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> ------------------------------
>
> Message: 3
> Date: Wed, 09 Nov 2016 18:05:21 +0000
> From: Jan-Frode Myklebust <janfrode at tanso.net>
> To: "gpfsug-discuss at spectrumscale.org"
> <gpfsug-discuss at spectrumscale.org>
> Subject: Re: [gpfsug-discuss] Tuning AFM for high throughput/high IO
> over _really_ long distances
> Message-ID:
> <CAHwPathy=4z=jDXN5qa3ys+Z-_7n=tsJh7cZ3ZKzFwQMG34zwg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Mostly curious, don't have experience in such environments, but ... Is this
> AFM over NFS or NSD protocol? Might be interesting to try the other option
> -- and also check how nsdperf performs over such distance/latency.
>
>
>
> -jf
>> ons. 9. nov. 2016 kl. 18.39 skrev Jake Carroll <jake.carroll at uq.edu.au>:
>>
>> Hi.
>>
>>
>>
>> I?ve got an GPFS to GPFS AFM cache/home (IW) relationship set up over a
>> really long distance. About 180ms of latency between the two clusters and
>> around 13,000km of optical path. Fortunately for me, I?ve actually got near
>> theoretical maximum IO over the NIC?s between the clusters and I?m
>> iPerf?ing at around 8.90 to 9.2Gbit/sec over a 10GbE circuit. All MTU9000
>> all the way through.
>>
>>
>>
>> Anyway ? I?m finding my AFM traffic to be dragging its feet and I don?t
>> really understand why that might be. I?ve verified the links and transports
>> ability as I said above with iPerf, and CERN?s FDT to near 10Gbit/sec.
>>
>>
>>
>> I also verified the clusters on both sides in terms of disk IO and they
>> both seem easily capable in IOZone and IOR tests of multiple GB/sec of
>> throughput.
>>
>>
>>
>> So ? my questions:
>>
>>
>>
>> 1. Are there very specific tunings AFM needs for high latency/long
>> distance IO?
>>
>> 2. Are there very specific NIC/TCP-stack tunings (beyond the type
>> of thing we already have in place) that benefits AFM over really long
>> distances and high latency?
>>
>> 3. We are seeing on the ?cache? side really lazy/sticky ?ls ?als?
>> in the home mount. It sometimes takes 20 to 30 seconds before the command
>> line will report back with a long listing of files. Any ideas why it?d take
>> that long to get a response from ?home?.
>>
>>
>>
>> We?ve got our TCP stack setup fairly aggressively, on all hosts that
>> participate in these two clusters.
>>
>>
>>
>> ethtool -C enp2s0f0 adaptive-rx off
>>
>> ifconfig enp2s0f0 txqueuelen 10000
>>
>> sysctl -w net.core.rmem_max=536870912
>>
>> sysctl -w net.core.wmem_max=536870912
>>
>> sysctl -w net.ipv4.tcp_rmem="4096 87380 268435456"
>>
>> sysctl -w net.ipv4.tcp_wmem="4096 65536 268435456"
>>
>> sysctl -w net.core.netdev_max_backlog=250000
>>
>> sysctl -w net.ipv4.tcp_congestion_control=htcp
>>
>> sysctl -w net.ipv4.tcp_mtu_probing=1
>>
>>
>>
>> I modified a couple of small things on the AFM ?cache? side to see if it?d
>> make a difference such as:
>>
>>
>>
>> mmchconfig afmNumWriteThreads=4
>>
>> mmchconfig afmNumReadThreads=4
>>
>>
>>
>> But no difference so far.
>>
>>
>>
>> Thoughts would be appreciated. I?ve done this before over much shorter
>> distances (30Km) and I?ve flattened a 10GbE wire without really
>> tuning?anything. Are my large in-flight-packets
>> numbers/long-time-to-acknowledgement semantics going to hurt here? I really
>> thought AFM might be well designed for exactly this kind of work at long
>> distance **and** high throughput ? so I must be missing something!
>>
>>
>>
>> -jc
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> gpfsug-discuss mailing list
>> gpfsug-discuss at spectrumscale.org
>> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>>
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