[gpfsug-discuss] CES node slow to respond

Matt Weil mweil at wustl.edu
Fri Mar 24 20:03:22 GMT 2017


also running version 4.2.2.2.

On 3/24/17 2:57 PM, Matt Weil wrote:


On 3/24/17 1:13 PM, Bryan Banister wrote:
Hi Vipul,

Hmm… interesting.  We have dedicated systems running CES and nothing else, so the only  thing opening files on GPFS is ganesha.  IBM Support recommended we massively increase the maxFilesToCache to fix the performance issues we were having.  I could try to reproduce the problem to investigate further, but the impact to users would not be appreciated.
Same with us the system only runs CES and NFS.  All open files 5.4 million where tied to it.  This excluded anything the system had open.

Setting such a high value for maxFilesToCache has direct impact on the token manager so fixing this would be very good.

Perhaps IBM could take a closer look at this without our involvement?
-Bryan

From: Vipul Paul [mailto:vpaul at us.ibm.com] On Behalf Of IBM Spectrum Scale
Sent: Friday, March 24, 2017 12:18 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org><mailto:gpfsug-discuss at spectrumscale.org>; Bryan Banister <bbanister at jumptrading.com><mailto:bbanister at jumptrading.com>
Subject: Re: CES node slow to respond

Hi Bryan,

Making sure Malahal's reply was received by the user group.

>> Then we noticed that the CES host had 5.4 million files open

This is technically not possible with ganesha alone. A process can only open 1 million files on RHEL distro. Either we have leaks in kernel or some other processes contributing to this.

Ganesha does keep NFSv3 files open and keep open for performance. It doesn't have a good logic to close them after some inactivity. It does close them if the number is close to max open files which is configurable.

PS: kNFS does open, read/write, and then close.  No caching in older versions. They did have a feature in a recent code to cache open files in NFSv3 as well.

Regards, The Spectrum Scale (GPFS) team

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From:        Bryan Banister <bbanister at jumptrading.com<mailto:bbanister at jumptrading.com>>
To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
Date:        03/23/2017 08:27 AM
Subject:        Re: [gpfsug-discuss] CES node slow to respond
Sent by:        gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org>
________________________________



Anybody from IBM willing/able to give us some explanation of why ganesha is holding open so many files?  Is this expected/needed/etc?

Or do we have to open a PMR to get some kind of explanation?
-B

-----Original Message-----
From: gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org> [mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Matt Weil
Sent: Thursday, March 23, 2017 10:24 AM
To: gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] CES node slow to respond

FYI all

We also ran into this after bumping maxFilesToCache.

Mar 22 13:02:37 ces1 ntpd[1191]: ./../lib/isc/unix/ifiter_ioctl.c:348:
unexpected error:
Mar 22 13:02:37 ces1 ntpd[1191]: making interface scan socket: Too many
open files in system

fix

sysctl -w fs.file-max=1000000


On 3/22/17 12:01 PM, Bryan Banister wrote:
> We had a similar issue and also were instructed by IBM Support to increase the maxFilesToCache to an insane value... Basically when the file cache gets full then the host will spend all of its cycles looking for a file to evict every time a new file is opened...  baaaah.
>
> Not sure why Ganesha has to keep so many files open... I can't believe our NFS clients actually keep that many open.  cNFS never needed this.
> -Bryan
>
> -----Original Message-----
> From: gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org> [mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Matt Weil
> Sent: Wednesday, March 22, 2017 11:43 AM
> To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
> Subject: [gpfsug-discuss] CES node slow to respond
>
> All,
>
> We had an indecent yesterday where one of our CES nodes slowed to a
> crawl.  GPFS waiters showed pre fetch threads going after inodes.
> iohist also showed lots of inode fetching.  Then we noticed that the CES
> host had 5.4 million files open.
>
> The change I made was to set maxStatCache=DEFAULT because it is linux.
> And set maxFilesToCache=10000000 it was set to 500000.  Then restarted GPFS.
>
> Is there something else we should change as well.
>
> Thanks
>
> Matt
>
>
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