Storage Management TEG: Questionnaire Level 1 - Philippe Charpentier

This twiki is to collect the input of Philippe Charpentier. Please answer the questions below. For more information, please refer to the Storage TEG main twiki.

Question 1

- In your view, what are the 3 main current issues in Storage Management (SM)?

My answer:

  1. Non conformance of SRM implementations with specifications
  2. Lack of robustness of SRM services, including inconsistencies between SRM information and SE (dCache in particular, including "files out of spaces")
  3. Lack of scalability of data access by protocol (related to bigger and bigger disks and limited throughput our of servers as well as lack of spindles)

Question 2

- What is the greatest future challenge which would greatly impact the SM sector?

My answer:

Have a "file:" access protocol with a real mounted file system to the disk servers ensuring scalability.

Question 3

- What is your site/experiment/middleware currently working on in SM?

My answer:

Question not clear... However, LHCb is using Castor, dCache and StoRM. DPM is in the coming future going to be used at some sites. We fully rely on SRM for accessing our data.

Question 4

- What are the big developments that you would like to see from your site/experiment/storage system in the next 5 years?

My answer:

Again not so clear, sorry... Do you mean a development done by our experiment (why?) or "seen from our experiment"? Assuming the latter... A resilient and scalable Storage system that would guarantee full synchronisation with the file/replica catalog (contact with the DM TEG), with a scalable file system. Of course replacing SRM with just a file path and implementing native ACLs for data security.

Question 5

- In your experience and area of competence, what are the (up to) 3 main successes in SM so far?

My answer:

  1. Surprising enough, and despite all its imperfections, SRM could be considered as a success, but is far from perfection (to say the least wink ).
  2. Tape backend reliability in Castor, dCache and StoRM
  3. Can't fins a third... may come later wink

Question 6

- In your experience and area of competence, what are the (up to) 3 main failures or things you would like to see changed in SM so far?

My answer:

  1. SRM wink because it was implemented for most SM as an add-on to an existing system without considering changing the way this system works. Therefore the lack of implementation of many agreed features in SRM v2.2 just because they didn't fit with the existing prejudice/implementation.
  2. Lack of scalability of data access by protocol, in particular for tape disk caches: disk size is not the parameter, but number of spindles and number of clients connected is the correct metrics. The bigger the disk, the less scalable they are...
  3. ??? SRM ??? wink

That's it!

Thanks! Feel free to edit again at any time, until the date of the kick-off meeting.

-- DanieleBonacorsi - November 2011

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Topic revision: r2 - 2011-11-08 - PhilippeCharpentier
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