1 Reforming Software Delivery Using P2P Technology Purvi Shah Advisor: Jehan-François Pâris Department of Computer Science University of Houston Jeffrey Morgan Miranda Mowbray John Schettino, Chandrasekar Venkatraman Enterprise Systems and Software Lab Hewlett-Packard

2 Central server HP’s Internal Managed Service department Waystations Edge servers Maintain all or few Linux distributions Software synchronization Software package delivery Customers Problem: Fast and Inexpensive Software Delivery

3 Access Logs - I Image downloads represents 71% of the total upload –Focus on sending large packages efficiently Large percentage of downloads for other packages –New mechanism should not hurt this performance

4 Access Logs - II Access patterns observed –New update packages –Requests by day of the week 17.5% of large files differ from other files only in name Huge similarities between different versions of source packages –Further efficiencies

5 Achieving Efficient Synchronization One – to – many problem Can we significantly improve performance? –Sure, combining P2P technology with rsync (currently used protocol and tool) –Use file swarming Chop files into chunks (similar to rsync) Disseminate files by exchanging chunks between peers Verify data integrity using hashes obtained from the server Rely on BitTorrent protocol

6 Using Emulab testbed Examine issues when using synchronization with swarming Large chunk sizes –Low per chunk overhead –Less opportunities to exploit similarity Tradeoff between exploiting similarity and improving swarm performance Experimental Results

7 Software Package Delivery Avoid custom applications for software package delivery –Several different types of applications used Decreasing customer request rate during the post flash crowd scenario –Increases the downloading time in a multiple file system as the server may have other workload Avoid consuming the customer upload bandwidth –Can we provide enough bandwidth in an alternate way Using Volunteer Assistance –Maximize the advantages, minimize the constraints

8 Using Volunteer Assistance Server Volunteers (partial) mirrors Software synchronization 1: Request Software package delivery Customers 2: Redirection 3: Send Tracker

9 Related Work Content Delivery Networks (Akamai, CORAL) Key differences –Customer is redirected to volunteer only when volunteer has the requested data –Server aided by tracker redirects the customer to the volunteers Full decentralization can make security and optimization hard when using volunteers Opportunity to make intelligent decisions at the tracker

10 Ongoing Work Load-balancing –Selection of volunteers to respond to customer requests –Tracker-based approach Tracker collects synchronization information –What files on what volunteers –What volunteers are currently synchronizing their repository –Readily available without much overhead Use this information to make better load balancing decisions Future: Study data placement policies required to handle volatile volunteers Allow individuals to donate idle machine time to improve the software delivery process Use access patterns to replicate the packages

11 Questions? Thank you