Hi,
We are running a test setup with 2 NSD Servers backed by 4 Dell
Powervaults MD3460s. nsd00 is primary serving LUNS of controller A of
the 4 powervaults, nsd02 is primary serving LUNS of controller B.
We are testing from 2 testing machines connected to the nsds with
infiniband, verbs enabled.
When we do dd from the NSD servers, we see indeed performance going to
5.8GB/s for one nsd, 7.2GB/s for the two! So it looks like GPFS is able
to get the data at a decent speed. Since we can write from the clients
at a good speed, I didn't suspect the communication between clients and
nsds being the issue, especially since total performance stays the same
using 1 or multiple clients.
I'll use the nsdperf tool to see if we can find anything,
thanks!
K
On 20/04/17 17:04, Knister, Aaron S. (GSFC-606.2)[COMPUTER SCIENCE CORP]
wrote:
Interesting. Could you share a little more about your architecture? Is
it possible to mount the fs on an NSD server and do some dd's from the
fs on the NSD server? If that gives you decent performance perhaps try
NSDPERF next
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General+Parallel+File+System+(GPFS)/page/Testing+network+performance+with+nsdperf
-Aaron
On April 20, 2017 at 10:53:47 EDT, Kenneth Waegeman
<[email protected]> wrote:
Hi,
Having an issue that looks the same as this one:
We can do sequential writes to the filesystem at 7,8 GB/s total ,
which is the expected speed for our current storage
backend. While we have even better performance with sequential reads
on raw storage LUNS, using GPFS we can only reach 1GB/s in total
(each nsd server seems limited by 0,5GB/s) independent of the number
of clients
(1,2,4,..) or ways we tested (fio,dd). We played with blockdev
params, MaxMBps, PrefetchThreads, hyperthreading, c1e/cstates, .. as
discussed in this thread, but nothing seems to impact this read
performance.
Any ideas?
Thanks!
Kenneth
On 17/02/17 19:29, Jan-Frode Myklebust wrote:
I just had a similar experience from a sandisk infiniflash system
SAS-attached to s single host. Gpfsperf reported 3,2 Gbyte/s for
writes. and 250-300 Mbyte/s on sequential reads!! Random reads were
on the order of 2 Gbyte/s.
After a bit head scratching snd fumbling around I found out that
reducing maxMBpS from 10000 to 100 fixed the problem! Digging
further I found that reducing prefetchThreads from default=72 to 32
also fixed it, while leaving maxMBpS at 10000. Can now also read at
3,2 GByte/s.
Could something like this be the problem on your box as well?
-jf
fre. 17. feb. 2017 kl. 18.13 skrev Aaron Knister
<[email protected] <mailto:[email protected]>>:
Well, I'm somewhat scrounging for hardware. This is in our test
environment :) And yep, it's got the 2U gpu-tray in it although even
without the riser it has 2 PCIe slots onboard (excluding the
on-board
dual-port mezz card) so I think it would make a fine NSD server even
without the riser.
-Aaron
On 2/17/17 11:43 AM, Simon Thompson (Research Computing - IT
Services)
wrote:
> Maybe its related to interrupt handlers somehow? You drive the
load up on one socket, you push all the interrupt handling to
the other socket where the fabric card is attached?
>
> Dunno ... (Though I am intrigued you use idataplex nodes as
NSD servers, I assume its some 2U gpu-tray riser one or something !)
>
> Simon
> ________________________________________
> From: [email protected]
<mailto:[email protected]>
[[email protected]
<mailto:[email protected]>] on behalf of
Aaron Knister [[email protected]
<mailto:[email protected]>]
> Sent: 17 February 2017 15:52
> To: gpfsug main discussion list
> Subject: [gpfsug-discuss] bizarre performance behavior
>
> This is a good one. I've got an NSD server with 4x 16GB fibre
> connections coming in and 1x FDR10 and 1x QDR connection going
out to
> the clients. I was having a really hard time getting anything
resembling
> sensible performance out of it (4-5Gb/s writes but maybe
1.2Gb/s for
> reads). The back-end is a DDN SFA12K and I *know* it can do
better than
> that.
>
> I don't remember quite how I figured this out but simply by
running
> "openssl speed -multi 16" on the nsd server to drive up the
load I saw
> an almost 4x performance jump which is pretty much goes
against every
> sysadmin fiber in me (i.e. "drive up the cpu load with
unrelated crap to
> quadruple your i/o performance").
>
> This feels like some type of C-states frequency scaling
shenanigans that
> I haven't quite ironed down yet. I booted the box with the
following
> kernel parameters "intel_idle.max_cstate=0
processor.max_cstate=0" which
> didn't seem to make much of a difference. I also tried setting the
> frequency governer to userspace and setting the minimum
frequency to
> 2.6ghz (it's a 2.6ghz cpu). None of that really matters-- I
still have
> to run something to drive up the CPU load and then performance
improves.
>
> I'm wondering if this could be an issue with the C1E state?
I'm curious
> if anyone has seen anything like this. The node is a dx360 M4
> (Sandybridge) with 16 2.6GHz cores and 32GB of RAM.
>
> -Aaron
>
> --
> Aaron Knister
> NASA Center for Climate Simulation (Code 606.2)
> Goddard Space Flight Center
> (301) 286-2776
> _______________________________________________
> gpfsug-discuss mailing list
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>
--
Aaron Knister
NASA Center for Climate Simulation (Code 606.2)
Goddard Space Flight Center
(301) 286-2776
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