1 / 24

Space allocations in NeST

Space allocations in NeST. Outline. Overview of NeST Space allocations Implementation Big picture Measurements and Future Work. Overview of NeST. Network storage server designed for the Grid Flexibility Unprivileged, user-level software Multiple protocols Chirp, GridFTP, FTP, HTTP, NFS

airlia
Download Presentation

Space allocations in NeST

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Space allocations in NeST

  2. Outline • Overview of NeST • Space allocations • Implementation • Big picture • Measurements and Future Work

  3. Overview of NeST • Network storage server designed for the Grid • Flexibility • Unprivileged, user-level software • Multiple protocols • Chirp, GridFTP, FTP, HTTP, NFS • Multiple concurrency models • Processes, threads, non-blocking • Portable

  4. Overview of NeST • Functionality • Exports Unix based file system • Space allocation ( Lot ) • Manageability • User management – Dynamic users • Security – GSI authentication

  5. Physical network layer Chirp FTP Grid FTP HTTP NFS Common protocol layer Storage Mgr Control flow Dispatcher Data flow Lot Mgr Concurrencies Transfer Mgr NeST structure Physical storage layer

  6. Why space allocations ? • Data generation and storage • Data intensive applications • Need to allocate space for temporary files • Data migration • Many simultaneous data flows • Competition for storage space • Possible that all flows end in partial transfers • Need to ensure at least one succeeds

  7. Space allocations in NeST • Lot – abstraction for space allocation • Create lot for a specified size and duration • User and group lots • Guaranteed and best-effort lots • Hierarchical lots

  8. Motivation for hierarchical lot • SRMs on top of NeSTs • Client requests streamlined through SRMs • SRMs create a large lot • SRMs distribute sub-lots among clients carved from the large lot

  9. Lot operations • Create, Delete, Update • MoveFile • Moves files across lots • AddUser, RemoveUser • Lot level access control • List of users allowed to request sub-lots • Attach / Detach • Associates a path to a lot

  10. Implementation - two choices • Rely on the underlying quota system • Kernel-assisted lot • Provide the space guarantee within NeST • User-level lot • A third choice? • Modify kernel

  11. Physical network layer Chirp FTP Grid FTP HTTP NFS Common protocol layer Storage Mgr Control flow Dispatcher Data flow Lot Mgr Concurrencies Transfer Mgr Physical storage layer Kernel-assisted lot Quota system

  12. Kernel-assisted lot • Quota system provides the guarantee • Chirp-like protocols pose no challenge • Aware of transfer size • GridFTP-like protocols ? • Transfer size may be unknown • Don’t worry at NeST level • Quota system watches disk writes

  13. Physical network layer Chirp FTP Grid FTP HTTP NFS Common protocol layer Storage Mgr Control flow Dispatcher Data flow Lot Mgr Concurrencies Transfer Mgr Physical storage layer User-level lot

  14. User-level lot • NeST provides the guarantee • Chirp-like protocols pose no challenge • GridFTP-like protocols ? • Iterative data transfer • Transfer manager repeatedly queries lot manager

  15. So which one ? • Kernel-assisted • Pros • Less complex • POSIX access • Cons • Needs root privileges • Depends on quota system – Less portability • Cannot distinguish among different allocations for the same user • Does not have a hierarchical organization

  16. So which one ? • User-level • Pros • Flexible, Portable • Hierarchical organization is easy • Easy to differentiate among lots for the same user • Cons • Difficult to provide POSIX access • Complexity in the transfer and lot managers

  17. Stork Request allocation Chirp allocations Chirp output Activate 3rd party put Chirp input NeST NeST NeST GridFTP/DiskRouter transfer Remote site Big picture SRM DAGMan Job

  18. Where are the overheads ? • Lot operations • Puts • Recovery

  19. Lot operations

  20. Puts using Chirp With increase in transfer size overhead is amortized

  21. Puts using GridFTP With increase in transfer size, overheads become comparable

  22. Recovery time Compaction reduces lot overhead to a manageable level

  23. Future Work • Advance reservations • Combo - Space and disk bandwidth reservation • Recovery management • Transaction based lot operations

  24. Questions ? • Demo on Wednesday • Room 3351, CS building, 9am – noon • More information available at • www.cs.wisc.edu/condor/nest • People • John Bent, Joseph Stanley, Nick LeRoy, Alain Roy • Miron Livny, Andrea Arpaci-Dusseau, Remzi Arpaci-Dusseau, Arie Shoshani

More Related