Thursday, February 3, 2011

Safety, Visibility, and Performance in a Wide-Area File System

Link to the paper:
http://usenix.org/events/fast02/full_papers/kim/kim.pdf

Presenter: Saakshi Verma
Reviewers: Duygu Sarikaya and Sandeep Venkatesh

6 comments:

  1. In the very beginning in the Introduction section, there is a mention that the Client writes are propagated to the secondary replica sites, i.e. WayStations, providing safety. Now, these are reconciled with the actual servers but these are just the update notifications i.e. metadata. Agreed that the updates can be done frequently, but then who does the actual updates with the servers? Are the actual updates reconciled to the server and are they required?

    ReplyDelete
  2. While in the process of updating a file is it possible for a mobile client to change it's WayStation? If it can change it's WayStation during the update process wont there be inconsistencies in the file?

    ReplyDelete
  3. In section 3, the authors state: "In order to provide copy semantics without actually copying during reconciliation, replicas hold reconciled
    updates in escrow." Is there a limit to the number of reconciled updates that can be held in escrow? if so what happens if the limit is exceeded? will information be lost?

    ReplyDelete
  4. In section 3.3, the authors state: "If each WayStation reconciles at a constant rate, all updates are globally visible within twice the longest reconciliation period." What happens if each WayStation does not reconcile at a constant rate? Approximately, when will updates be globally visible?

    ReplyDelete
  5. Since the fluid replication prototype was developed almost a decade ago, have improvements been implemented? has any other prototype been developed based on the fluid replication model? In terms of replication cost can servers utilizing fluid replication now reconcile 150 log records in less than 1.1 seconds?

    ReplyDelete
  6. @ Varun , the authors say that the WayStations send propogate the contents as well however unlike update metadata they do not propagate file contents to the server immediately, but they defer them to take advantage of the low incidence of sharing in file systems.

    ReplyDelete