LISTSERV mailing list manager LISTSERV 16.5

Help for XROOTD-L Archives


XROOTD-L Archives

XROOTD-L Archives


XROOTD-L@LISTSERV.SLAC.STANFORD.EDU


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Monospaced Font

LISTSERV Archives

LISTSERV Archives

XROOTD-L Home

XROOTD-L Home

XROOTD-L  April 2008

XROOTD-L April 2008

Subject:

Re: load problem with redirector at GridKa

From:

"Andrew Hanushevsky" <[log in to unmask]>

Date:

28 Apr 2008 17:12:35 -0700Mon, 28 Apr 2008 17:12:35 -0700

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (136 lines)

Hi Florian,

There are several issues here.

1) More requests are comming to the redirector than can be dispatched. It
appears that you average somewhere around 5/second. That means you likely
have peeks substantially greater. If you run a single redirector, perhaps
it's time to now run two redirectors. The client will automatically load
balance themselves between the two. The simples way to do this is to assign
both IP address to the same DNS name. You should *not* use a load-balancing
DNS to this this. The second IP address is simply added as another
interface. Anyway, hitting the thread limit is not fatal. It just means that
your load has increased to the point that the redirector can't effeciently
handle the incomming traffic. You can get additional headroom by specifying:

xrd.timeout read 1

Please specify this *only* for the redirector as it will likely have
negative effects for data servers. This will give you up to 80% improvement
in thread turn-over. Mind you, we haven't really tried using this tuning
option for this problem.

2) The more serious problem is indicated by the message:

080422 03:04:21 001 XrdAccept: Unable to perform accept.; too many open
files in system

This is due to one of two reasons: a) the redirectors file descriptor limit
is set too low (the actual number will be written to the log upon start-up),
b) the overall system limit was exceeded. I doubt that (b) is the problem.
So, assuming tcsh, a limit -h will show what the default "discriptors" hard
limit is (the server tries to use the hard value). If it's below 16K you
should ask your admins to increase to at least 16k (32k will likely mean you
won't have to worry about for some time).

3) Unless you really need to trace redirects, I normally recommend turing it
off. It serializes the processing path and generally slows thigs down.

Let me know how it goes.

Andy


----- Original Message -----
From: "Florian Bernlochner" <[log in to unmask]>
To: <[log in to unmask]>
Cc: <[log in to unmask]>
Sent: Monday, April 28, 2008 2:23 PM
Subject: load problem with redirector at GridKa


> Hi there,
>
> since last week I obseve some strange load related problem with the
> xrootd cluster at GridKa. During fairly 'normal' load [1] the
> redirector reaches its Thread limit [2]. I set it to maximum but the
> problems reoccurred several times [3]. It almost seems, that the
> scheduler does not flush the threads in time, but I guess might have
> more insight on this issue. Well feel free to share any kind of advice
> or wisdom :-)
> The cluster has 12 servers (2 in staging mode) and all run on
> 20071101-0808p1.
>
> Florian
>
>
>
> [1] # of redirs per 10 minute
> http://iktp.tu-dresden.de/~petzold/work/GridKa/xrootd/redirs.png
> # of logins per 10 minute
> http://iktp.tu-dresden.de/~petzold/work/GridKa/xrootd/logins.png
>
> [2] Log:
>
> 080422 00:10:41 27010 odc_send2Man:
> mcprod.2729:[log in to unmask] redirected to
> f01-010-105.gridka.de:1094 by l01-001-110
> path=/store/cfg/2008/03/CfgDB-20080328T123723.root
> 080422 00:10:42 27010 XrdScheduler: Thread limit has been reached!
> 080422 00:10:42 27010 odc_send2Man:
> mcprod.9859:[log in to unmask] redirected to
> f01-010-105.gridka.de:1094 by l01-001-110
> path=/store/cfg/2008/03/CfgDB-20080328T123723.root
> 080422 00:10:42 27010 odc_send2Man:
> mcprod.907:[log in to unmask] redirected to
> f01-010-105.gridka.de:1094 by l01-001-110
> path=/store/cfg/2008/03/CfgDB-20080328T123723.root
> 080422 03:04:21 001 XrdAccept: Unable to perform accept.; too many
> open files in system
> 080422 03:04:21 001 XrdAccept: Unable to perform accept.; too many
> open files in system
> 080422 03:04:21 001 XrdAccept: Unable to perform accept.; too many
> open files in system
> 080422 03:04:21 001 XrdAccept: Unable to perform accept.; too many
> open files in system
>
> [3] Redirector Config:
>
> olb.allow host babar*.gridka.de
> olb.allow host f01-*.gridka.de
> olb.path s /store
> olb.path w /prod
> olb.path w /gaffertape
> olb.port 3121
> olb.sched cpu 100
> olb.wait
>
> xrd.sched mint 8 maxt 4095 avlt 512 idle 780
>
> xrootd.export /prod
> xrootd.export /store
> xrootd.export /gaffertape
> xrootd.fslib /home/xrootd/software/current/lib/libXrdOfs.so
>
> odc.trace redirect
> #olb.trace all
> #oss.trace all
> #xrd.trace all
> #xrootd.trace all
>
>
>
> --
> ------------------------------------------------------------------
> Humboldt-Universität zu Berlin
> Department of Physics
> BaBar, Prof. H. Lacker and Prof. M. Kobel
> Newtonstr. 15, 12489 Berlin, Germany
> Web: slac.stanford.edu/babar
> ------------------------------------------------------------------
>
>



Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

March 2024
February 2024
January 2024
December 2023
November 2023
October 2023
September 2023
August 2023
July 2023
June 2023
May 2023
April 2023
March 2023
February 2023
January 2023
December 2022
October 2022
September 2022
August 2022
July 2022
June 2022
May 2022
April 2022
March 2022
February 2022
January 2022
December 2021
November 2021
October 2021
September 2021
August 2021
July 2021
June 2021
May 2021
April 2021
March 2021
February 2021
January 2021
December 2020
November 2020
October 2020
September 2020
August 2020
July 2020
June 2020
May 2020
April 2020
March 2020
February 2020
January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
July 2009
June 2009
May 2009
April 2009
March 2009
January 2009
December 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
September 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004

ATOM RSS1 RSS2



LISTSERV.SLAC.STANFORD.EDU

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager

Privacy Notice, Security Notice and Terms of Use