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:

Proportional Font

LISTSERV Archives

LISTSERV Archives

XROOTD-L Home

XROOTD-L Home

XROOTD-L  June 2011

XROOTD-L June 2011

Subject:

Re: inbound traffic

From:

Kyle Fransham <[log in to unmask]>

Date:

27 Jun 2011 09:29:59 -0400Mon, 27 Jun 2011 09:29:59 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (181 lines)

Hi Andy,

Thanks very much for convincing us that the traffic is not xrootd 
related.  On closer inspection, we found that this particular node was 
misconfigured to read the underlying lustre FS on the public interface, 
which is why the inbound traffic scaled so perfectly with the outbound 
xrootd traffic.

All the best!

Kyle

On 06/24/2011 04:07 PM, Andrew Hanushevsky wrote:
> Hi Kyle,
>
> The summary counts are consistent. A read request is 24 bytes in length.
> So, we find
>
> 37184778462/1548943168 = 24.007 (as expected)
>
> The average payload in response:
>
> 26610785518162/1548943168 = 17179 (which looks pretty good)
>
> However, this is misleading. Looking at the sample of recvfrom's we find:
>
>             File#    Offset           Length
> 0600 0bc5 00000000 0000000000d74e00 0008a400 = 566272 bytes
> 1f00 0bc5 00000000 0000000000dff200 00003e00 =  15872 bytes
> 0500 0bc5 00000000 0000000000e03000 00004400 =  17408 bytes
> 0500 0bc5 00000000 0000000000e07400 00001400 =   5120 bytes
> 1f00 0bc5 00000000 0000000000e08800 00001400 =   5120 bytes
> 0600 0bc5 00000000 0000000000e09c00 00001400 =   5120 bytes
>
> So, you likely do a lot of small reads with the very large reads pushing
> up the average. That said, I would still suspect the monitoring at this
> point.
>
> Andy
>
> On Fri, 24 Jun 2011, Kyle Fransham wrote:
>
>> Hi Andy,
>>
>> On 06/23/2011 04:28 PM, Andrew Hanushevsky wrote:
>>> Hi Kyle,
>>>
>>> What we need to do is find out what the inbound traffic really is. So, some
>>> more questions:
>>>
>>> 1) On your graph is that bytes in/out or packets in/out. If this is packets
>>> then the graph is likely correct and you are simply doing a lot of very
>>> small reads.
>> That's definitely bytes, not packets on the graph.
>>> 2) To find out a bit more statistics you can connect to the xrootd server
>>> using the xrd command. Do the following:
>>>
>>> xrd<the_xrootd_server>
>>> query 1 lp
>>> exit
>>>
>>> The find the values between<in></in>   and<out></out>   that will give you
>>> number of bytes in and number out. We need to see if that is reasonable
>>> compared to actual requests which you will find between<rd></rd>   and
>>> <wr></wr>   (read/write counters).
>> <rd>1548943168</rd>
>> <wr>0</wr>
>> <in>37184778462</in>
>> <out>26610785518162</out>
>>
>> So writes are 0, as expected.  Inbound traffic is three orders of magnitude
>> less than outbound, which doesn't correspond to our monitoring, but looks
>> good.
>>
>>> 3) If those still seem not to correspond then we can look at the actual
>>> xrootd kernel calls using strace. For instance:
>>>
>>> strace -f -xx -ttt -p<pid>   -e trace=network 2>&1 | grep  'recv('>
>>> <outfile>
>> Okay, so I see no calls to 'recv(' in the strace.  However, I do see calls to
>> 'recvfrom('  that look like this:
>>
>> [pid 16211] 1308923304.005638 recvfrom(19,
>>
> "\x06\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd7\x4e\x00\x00\x08\xa4\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>> [pid 16211] 1308923304.045490 recvfrom(19,
>> "\x1f\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xdf\xf2\x00\x00\x00\x3e\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>> [pid 16211] 1308923304.046110 recvfrom(19,
>> "\x05\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe0\x30\x00\x00\x00\x44\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>> [pid 16211] 1308923304.999048 recvfrom(19,
>> "\x05\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe0\x74\x00\x00\x00\x14\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>> [pid 16211] 1308923304.999260 recvfrom(19,
>> "\x1f\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe0\x88\x00\x00\x00\x14\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>> [pid 16211] 1308923305.000027 recvfrom(19,
>> "\x06\x00\x0b\xc5\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe0\x9c\x00\x00\x00\x14\x00\x00\x00\x00\x00",
>> 24, 0, NULL, NULL) = 24
>>
>>> This will capture server recv() requests (inbound traffic). No need to run
>>> this more than a minute or two.
>>>
>>> 4) If that doesn't reveal anything then the only other option is that there
>>> really is something else on that machine that is accepting incoming
>>> traffic.
>>> If it isn't udp then netstat should show you who that might be.
>> At a first glance, netstat doesn't show any real flags.  Also, xrootd really
>> is the only thing running on this machine, and we see lots of input whenever
>> a user runs jobs, (i.e. reads data from xrootd) and no input otherwise.  So
>> the two are at least correlated...
>>
>> Thanks for your help!
>>
>> Kyle
>>> Andy
>>>
>>>
>>> -----Original Message-----
>>> From: Kyle Fransham
>>> Sent: Thursday, June 23, 2011 1:05 PM
>>> To: Andrew Hanushevsky
>>> Cc: xrootd-l
>>> Subject: Re: inbound traffic
>>>
>>> Hi Andy,
>>>
>>> This is a machine at UVic that we use to serve BaBar xrootd files to
>>> virtual machines that we spawn in the cloud.  It's running little else
>>> besides xrootd.  Any traffic on the external interface (the plot that I
>>> sent) is xrootd.  We see very high inbound traffic almost all of the time.
>>>
>>> On the back end, we have 10TB or so of data in a lustre filesystem
>>> that's distributed across multiple workers.  Since this is a distributed
>>> filesystem, we expect (and we do see) traffic on the internal interface
>>> that's associated with the reading of xrootd collections.  But we don't
>>> expect to see that externally...
>>>
>>> What else can I tell you about this machine/setup to help diagnose the
>>> problem?
>>>
>>> Thanks,
>>>
>>> Kyle
>>>
>>> On 06/23/2011 03:36 PM, Andrew Hanushevsky wrote:
>>>> Hi Kyle,
>>>>
>>>> There should be little inbound traffic unless that machine is used for
>>>> more
>>>> than just xrootd services. What machine are we talking about?
>>>>
>>>> Andy
>>>>
>>>> -----Original Message-----
>>>> From: Kyle Fransham
>>>> Sent: Thursday, June 23, 2011 7:48 AM
>>>> To: xrootd-l
>>>> Subject: inbound traffic
>>>>
>>>> Hi all,
>>>>
>>>> We've got a single xrootd server serving out BaBar root files over the
>>>> WAN.  We notice that there is a lot of inbound traffic, even though our
>>>> files are exported read-only.  Attached is a network plot showing the
>>>> traffic on the xrootd interface for four simultaneous user analysis
>>>> jobs.  (In case you can't see the attachment, the inboud traffic tends
>>>> to be about 75% of the outbound traffic.)
>>>>
>>>> Is this expected behaviour?
>>>>
>>>> Thanks,
>>>>
>>>> Kyle
>>>>



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

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