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  February 2008

XROOTD-L February 2008

Subject:

Re: Proof performance with different storage schemas

From:

Sergey Panitkin <[log in to unmask]>

Reply-To:

[log in to unmask]

Date:

20 Feb 2008 12:46:54 -0500Wed, 20 Feb 2008 12:46:54 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (98 lines)

Hi Pablo,

Interesting study!
Thanks for sharing these results.

It would be also nice to have more information about CPU load, network 
I/O, memory consumption, etc during the tests.
Performance in events/s alone is usually not a very revealing number and 
does not tell directly what part of the system influenced performance 
scaling.

I would like to comment on your conclusions a bit.

If you plan to build a one node PROOF farm, then you probably should go 
with centralized storage.
If you are looking at something that scales up, the decision is not that 
straightforward.

The problem is to balance data intake rate of your farm with the 
bandwidth provided by a given storage solution.

A canonical ball park number for a root job read rate is about 10 MBytes/s.
If you consider, say, 10 node farm with 8 cores per node, each core 
running I/O bound proof worker process, then your sustained input 
bandwidth demand will be about 800 MB/s.
If you go with a centralized storage solution you might have a problem.	
Such load will definitely kill your typical 1Gbit/s local switch and is 
likely to strain your site's network infrastructure.

Now, expand your imaginary PROOF farm to 100 nodes.

The point is that network quickly becomes a bottleneck.

If you have or can cheaply build network infrastructure that can sustain 
such loads, then  you are in good shape and can proceed with centralized 
storage. Otherwise local distributed storage is your only solution.

For your particular case - one disk can sustain approximately 4 PROOF 
jobs. That usually means that your jobs have read rate of about 5 MB/s.
So, second hard drive (RAIDed or not) should help to feed 8 jobs, which 
seems to be an optimal number of jobs per node in your configuration anyway.
One 500GB extra disk cost about $100 these days.
Add one to each node and now you can expand your farm without much worries.

You might find some information on PROOF scaling studies in talks given 
at the last PROOF workshop. http://root.cern.ch/root/PROOF2007/

Cheers,
	Sergey




Pablo Fernandez wrote:
> Thanks!
> 
> Unfortunately the xrootd protocol does not work as expected in dcache. The 
> idea was to use a conventional SE to store all the data for Tier2 and also 
> serve files to the Tier3... I don't know if Lustre implements an xrootd door 
> as well, maybe in a few months I'll try that.
> 
> BR/Pablo
> 
> On Wednesday 20 February 2008 11:40, Fabrizio Furano wrote:
>> Hi Pablo,
>>
>>   that's very interesting, and I agree completely with your conclusion,
>> i.e. in most cases the lan data access is more efficient and scales
>> better with respect to local disk access. Many times this is not very
>> well understood by people, always striving to keep local files at any cost.
>>
>>   It would be very interesting to have a comparison between the
>> performance in proof between a dcache storage and an analogous xrootd
>> storage, which is the default solution for that. With the same pool of
>> workers of course.
>>
>>   From what I've understood, dcache uses a read ahead mechanism (at the
>> client side), while xrootd uses a scheme which is mixed with informed
>> async prefetching.
>>
>>   Fabrizio
>>
>> Pablo Fernandez ha scritto:
>>> Hi all,
>>>
>>> I would like to share with you some information about my testings of
>>> performance in Proof with different storage schemas.
>>>
>>> http://root.cern.ch/phpBB2/viewtopic.php?t=6236
>>>
>>> I have translated this topic to the Proof Forum since seems to me more
>>> Proof-related than just xrootd, I hope you don't mind.
>>>
>>> BR/Pablo
> 


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

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